bluuebunny/crossref_metadata_2025 huggingface dataset:
PROTEIN METHYLATION BY CEREBRAL TISSUE
Authors: Miyake M. , Kakimoto Y.
Published: October 2006

Abstract— Transfer of the methyl group of S‐adenosyl [Me‐14C]methionine into cerebral proteins, an encephalitogenic protein and histones was studied using extracts of bovine and rat brains. The brain extract contains multiple substrate proteins and their lysine and arginine residues were methylated to form Ne‐mono‐, ‐di‐ and ‐trimethyl‐lysine and NG‐mono‐, NG, NG‐ and NG,NG‐dimethylarginine residues respectively, at different rates. The enzyme which catalyses the methylation of arginine residues was differentiated by ammonium sulphate fractionation from that methylating lysine residues. Methylation of arginine and lysine residues of proteins was stepwise in general, from mono‐ to dimethyl‐arginine and from mono‐ to di‐ and trimethyl‐lysines. Two different enzymes which methylate histone and the encephalitogenic basic protein respectively were obtained from the cytoplasmic fraction of rat brain and their enzymic properties were examined.
CHEMICAL, ENZYMATIC AND ULTRASTRUCTURAL CHARACTERIZATION OF 5‐HYDROXYTRYPTAMINE‐CONTAINING NEURONS FROM THE GANGLIA OF APLYSIA CALIFORNICA AND TRITONIA DIOMEDIA
Authors: Weinreich D. , McCaman Marilyn W. , McCaman R. E. , Vaughn J. E.
Published: October 2006

Abstract— Several identified neurons in Aplysia and Tritonia ganglia were shown to contain measurable quantities (4–6 pmol/cell body) of 5‐hydroxytryptamine (5‐HT). A metabolic correlate for the limited distribution of 5‐HT among the neurons of Tritonia is provided by the finding that the enzyme, aromatic acid decarboxylase (AAD), is 500 times more active in nerve cells containing 5‐HT than in neurons devoid of the amine. Although all Aplysia neurons have some AAD activity, 5‐HT cell bodies in this species are 10‐fold more active than cell bodies which do not contain 5‐HT. The cytoplasm of 5‐HT cell bodies in Aplysia and Tritonia characteristically contains granules that have minimum diameters of approx. 1000 Å and eccentric opaque cores. This type of granule was not found in somata which did not contain measurable 5‐HT. These data illustrate the metabolic and morphological specialization in 5‐HT‐containing neurons of molluscs.
RAPIDLY REASSOCIATING DNA OF RAT BRAIN
Authors: Ranjekar P. K. , Murthy M. R. V.
Published: October 2006

Abstract— DNA's were isolated from brains of rats at different stages of growth and were fractionated on hydroxyapatite columns on the basis of their denaturation and reassociation properties. The results indicate that rat brain DNA had a heterogeneous population of base sequences. Approximately 10 per cent of the total DNA exhibited rates of reassociation characteristic of repetitive DNA. Differences were also observed in the pattern of denaturation of brain and liver DNA's of newborn and adult rats.
An ATP pool associated with adenyl cyclase of brain tissue
Authors: Shimizu H. , Okayama H.
Published: October 2006

Radioactive adenine has been frequently used to label cyclic adenosine 3′, 5′‐monophosphate (cAMP) in diverse cells and tissues (Kuo and DeRenzo, 1969; Shimizu, Daly and Creveling, 1969, Brooker, 1971). We have previously reported that cAMP from the guinea‐pig cerebral cortex is derived from a precursor pool of adenine nucleotides which is more highly labelled than the bulk cellular ATP (Shimizu, Creveling and Daly, 1970a). The present study was carried out to throw additional light on the property of the precursor pool. Levels of cAMP and ATP and specific activities of [14C]cAMP and [14C]ATP were determined simultaneously in cerebral slices which were prelabelled with [14C]adenine and subsequently incubated with veratridine, histamine or adenosine.
AXONAL TRANSPORT OF CATECHOLAMINE SYNTHESIZING AND METABOLIZING ENZYMES
Authors: Wooten G. F. , Coyle J. T.
Published: October 2006

The rates of accumulation of the catecholamine synthesizing and metabolizing enzymes proximal to a ligation on the sciatic nerve of the rat were studied. Dopamine‐β hydroxylase (EC 1.14.2.1) and tyrosine hydroxylase (EC 1.14.3a) accumulated at a similar rapid rate, and catechol‐O‐methyl‐transferase (EC 2.1.1.6), choline acetyltransferase (EC 2.3.1.6) and monoamine oxidase (EC 1.4.3.4) accumulated at the same slow rate, whereas DOPA decarboxylase (EC 4.1.1.26) accumulated at an intermediate rate. Based on clearance of the rapidly accumulating enzymes, absolute flow rates were estimated to be: 106‐167 mm/24 h for tyrosine hydroxylase; 138‐185 mm/24 h for dopamine‐β‐hydroxylase; and 36‐86 mm/24 h for DOPA decarboxylase. In contrast, the mean rate of transport of the slowly accumulating enzymes (monomine oxidase, catechol‐O‐methyltransferase and choline acetyltransferase) was approximately 3 mm/24 h. Colchicine and vinblastine completely blocked the axonal transport of both the rapidly and slowly transported enzymes. Studies of the subcellular distribution of each enzyme failed to confirm the suggestion that particulate enzymes are transported rapidly and soluble enzymes slowly. Our results suggest that the transport and inactivation of dopamine‐β‐hydroxylase, DOPA decarboxylase, and tyrosine hydroxylase are under different controls than monoamine oxidase and catechol‐O‐methyltransferase.
SUBCELLULAR AND SUBMICROSOMAL DISTRIBUTION OF GLYCOLIPID‐SYNTHESIZING TRANSFERASES IN YOUNG RAT BRAIN
Authors: Neskovic N. M. , Sarlieve L. L. , Mandel P.
Published: October 2006

The subcellular and submicrosomal distributions of four glycolipid‐synthesizing transferases were studied in young rat brains.

(1) Two galactosyl transferases involved in the synthesis of cerebrosides, the cerebroside sulphotransferase which catalyses the synthesis of sulphatides, and the glucosyl transferase which plays an important role in the ganglioside biosynthesis were localized essentially in the microsomal fraction. Only low activities were detected in the crude mitochondrial and synaptosome‐enriched fractions.

(2) A comparison of the activities of these enzymes in the crude myelin and two myelin subfractions showed that the galactosyl transferases and the cerebroside sulphotransferase had similar activities in the crude myelin and myelin‐like fractions. A considerable galactosyl transferase activity was found in purified myelin. In this respect these two enzymes were different from cerebroside sulphotransferase, whose activity was much lower in purified myelin. On the other hand, glucosyl transferase had a relatively low specific activity in all three myelin fractions. Analysis of different markers showed that the activities were considerably higher than those expected from the maximum microsomal contamination calculated.

(3) Subfractionation of the microsomes demonstrated that the galactosyl transferases were more concentrated in the lower parts of the gradient, containing vesicles with attached ribosomes. Cerebroside sulphotransferase and glucosyl transferase were found predominantly in the upper and intermediate parts of the gradient, which were composed essentially of smooth‐surfaced vesicles and membrane fragments. Chemical analysis of submicrosomal fractions confirmed the morphological observations.
EFFECTS OF CONVULSANTS ON CORTICAL ADENOSINE TRIPHOSPHATASES1
Authors: Brown Donna J. , Stone W. E.
Published: October 2006

Since inhibitors of Na‐K‐ATPase (EC 3.6.1.4) often produce epileptogenic foci on local application to cerebral regions, experiments were designed to determine whether systemic convulsants generally inhibit cortical ATPases either directly or indirectly. Injected convulsants (methionine sulphoximine, pentetrazole, picrotoxin, thiosemicarbazide and methyl fluoroacetate) did not alter the Na‐K‐ATPasc or Mg‐ATPase activities as measured in homogenates of specimens taken from the cerebral cortex of the dog. Picrotoxin had measurable inhibitory effects when added to a homogenate in vitro, but at a concentration higher than would probably be attained in the brain in vivo after a convulsant dose. Other systemic convulsants added in vitro were without effects on ATPase activities. Cortical tissue sampled after freezing in situ showed significantly higher ATPase activities than did tissue frozen after excision.
AXOPLASMIC TRANSPORT OF AROMATIC l‐AMINO ACID DECARBOXYLASE (EC 4.1.1.26) AND DOPAMTNE β‐HYDROXYLASE (EC 1.14.2.I) IN RAT SCIATIC NERVE
Authors: Dairman W. , Geffen L. , Marchelle Mary
Published: October 2006

The axoplasmic transport of aromatic l‐amino acid decarboxylase and dopamine β‐hydroxylase, two enzymes involved in the biosynthesis of catecholamines, was studied in rat sciatic nerve. The two enzymes exhibited markedly different axoplasmic flow characteristics, since dopamine β‐hydroxylase activity accumulated on the proximal side of a ligation nearly three times as fast as aromatic l‐amino acid decarboxylase activity. Distally dopamine β‐hydroxylase activity remained essentially constant for 24 h, whereas aromatic l‐amino acid decarboxylase activity fell precipitously. Evidence was obtained to rule out the possibility that differences in the rate of inactivation of the two enzymes could account for the different rates of accumulations observed. The conclusion, that aromatic L‐amino acid decarboxylase and dopamine β‐hydroxylase are transported in sympathetic nerve at different rates is discussed in relation to the biosynthesis of norepinephrine.
DIFFERENTIAL INCORPORATION OF [3H]LYSINE INTO VISUAL CORTEX PROTEIN FRACTIONS DURING FIRST EXPOSURE TO LIGHT
Authors: Richardson K. , Rose S. P. R.
Published: October 2006

—A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose, 1972) was achieved by polyacrylamide gel electrophoresis using a double‐labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.
CEREBELLAR DEVELOPMENT IN THE RAT AFTER EARLY POSTNATAL DAMAGE BY METHYLAZOXY‐METHANOL: DNA, RNA AND PROTEIN DURING RECOVERY
Authors: Chanda Rita , Woodward D. J. , Griffin Susan
Published: October 2006

—Total cerebellar DNA, RNA, protein and wet weight were determined for normal cerebellum and for cerebellum damaged early in postnatal development by the neurotoxic action of the drug methylazoxymethanol (MAM) acetate. Injections of a 10 mg/kg dose of the drug were given on postnatal days 1, 2, 3 and 4 as a means of inducing a transient insult to the proliferating stem cell population of the external granular layer. Cerebellar DNA and other quantitative measures were reduced to 50 per cent of normal at day 7. Growth in the MAM‐treated cerebellum was relatively more rapid than in normals so that the eventual deficit in the adult was 80 per cent of normal. We concluded that early postnatal transient injury of the developing cerebellum is followed by a regenerative phase of repair but that quantitatively significant mitosis in the injured cerebellum ceases normally at about post‐natal day 17. The conditions evaluated in this investigation may serve as a model for other types of injury induced by drugs, irradiation, viruses or nutritional factors.
ELECTROPHORETIC CHARACTERIZATION OF LEUCINE‐, GLUCOSAMINE‐ AND FUCOSE‐LABELLED PROTEINS RAPIDLY TRANSPORTED IN FROG SCIATIC NERVE
Authors: Edström A. , Mattsson H.
Published: October 2006

—[3H]Leucine, [3H]glucosamine and [3H]fucose were incorporated in vitro into proteins in frog sciatic ganglia and subsequently transported at a rapid rate along the sciatic nerve towards a ligature, in front of which they accumulated. The synthesis of transported fucose‐labelled proteins is closely linked to protein synthesis but is not dependent on RNA synthesis, as judged by effects after incubation for 17 h in the presence of cycloheximide and actinomycin D. Labelled ganglionic as well as transported material were solubilized in sodium dodecyl sulphate and characterized by polyacrylamide gel electrophoresis. The bulk of ganglionic proteins, labelled with any of the precursors used, had molecular weights exceeding 40,000. The radioactivity patterns of leucine‐ and glucosamine‐labelled ganglionic proteins showed similarities with dominant peaks corresponding to molecular weights of about 75,000 and 50,000. The last peak was almost lacking in fucose‐labelled ganglionic components. Leucine‐ and glucosamine labelled‐transported proteins exhibited characteristic and similar electrophoretic distributions in contrast to the pattern of fucose‐labelled nerve proteins, which was more polydisperse. The most conspicious nerve proteins corresponded to molecular weights of about 75,000 and 18,000. There was a remarkable agreement in the profile of leucine‐labelled transported nerve proteins and fucose‐labelled ganglionic proteins. In the light of these observations the possibility that glycoproteins constitute a large part of rapidly transported proteins will be discussed.
THE BLOCKAGE OF AXOPLASMIC FLOW OF PROTEINS BY COLCHICINE AND CYTOCHALASINS A AND B
Authors: McGregor A. M. , Komiya Y. , Kidman A. D. , Austin L.
Published: October 2006

Abstract— Colchichine blocks axoplasmic flow of proteins in chicken sciatic nerve. The slow component is more effectively blocked than the fast. The colchicine effect on slow flow is independent of the time delay between colchicine injection and that of the [14C]‐leucine used to measure flow, over a period extending from 2 h after to 9 days before the leucine. It is still effective, but to a lesser degree, after a period of 27 days. There is little effect on the fast component when the colchicine is administered after leucine. When given before leucine the effect is not pronounced up to a time interval of 1 day. Maximum blockage was obtained with longer intervals of up to 27 days. These results are discussed in relation to the involvement of the microtubules in both slow flow and rapid flow.

The effect of both cytochalasins A and B on slow and rapid protein flow has also been studied. Neither drug had any significant effect on slow flow. Cytochalasin A reduced the amount of protein flowing at the rapid rate to a small extent when administered 2 h before [14C]leucine. Cytochalasin B also caused a similar reduction and this effect was independent of dose over the ranges of doses used. The cytochalasin B diminished the incorporation of amino acid into protein in the spinal cord and it has been concluded that these results are due to a membrane effect which reduces uptake of amino acid rather than a direct effect on neurofilaments in the axons.
INCORPORATION OF PHENYLALANINE AS A SINGLE UNIT INTO RAT BRAIN PROTEIN: RECIPROCAL INHIBITION BY PHENYLALANINE AND TYROSINE OF THEIR RESPECTIVE INCORPORATIONS
Authors: Barra H. S. , Arce C. A. , Rodriguez J. A. , Caputto R.
Published: October 2006

Abstract— Of seven amino acids studied, glutamic acid and phenylalanine were incorporated in highest amounts into the hot‐TCA‐insoluble material of the 100,000 g supernatant fraction of rat brain homogenate. The system for incorporation of phenylalanine was RNase‐insensitive and required ATP (apparent Km= 0.64 mm), KC1 (apparent Km= 14 mm) and MgCl2 (optimal concentration range 4‐15 mm). The apparent Km for phenylalanine was 2.9 mm. [14C]Phenylalanine did not undergo modification before incorporation. Tyrosine and phenylalanine inhibited the incorporation, respectively, of [14C]phenylalanine and [14C]tyrosine when incubated simultaneously or successively. The Km and Kt (3.3 mm) values for phenylalanine in the incorporation reaction and as inhibitor of the incorporation of [14C]tyrosine were similar. We suggest that both the enzyme and the acceptor for the incorporation of these two amino acids are the same. [14C]Phenylalanine and [14C]tyrosine entered into COOH‐terminal positions in the reactions described. Brain exhibited a 25‐ to 100‐fold higher capacity to incorporate phenylalanine than that of liver, kidney or thyroid. The acceptor capacity in rat brain rapidly decreased from day 5 to day 15 of postnatal age and then slowly until age 150 days.
ADENOSINE 3′,5′‐MONOPHOSPHATE IN GUINEA PIG CEREBRAL CORTICAL SLICES: EFFECT OF BENZODIAZEPINES
Authors: Schultz J.
Published: October 2006

Several benzodiazepines, diazepam, chlordiazepoxide, desmethyldiazepam, methyloxazepam and oxazepam, potentiate the accumulation of cyclic AMP elicited by histamine and histamine: noradrenaline in cerebral cortical slices of guinea pig. In addition, these drugs increase basal levels of cyclic AMP by about 100 per cent. When adenosine is used to stimulate cyclic AMP formation only diazepam, desmethyldiazepam and methyloxazepam are increasing cyclic AMP levels significantly over respective controls. The order of potency is: diazepam > desmethyldiazepam > methyloxazepam > oxazepam > chlordiazepoxide. Diazepam decreases the rate of degradation of cyclic AMP after removal of the stimulatory agents (histamine : noradrenaline). Dose response curves for diazepam under two stimulatory conditions are shown. A significant effect is obtained at 50 μm‐diazepam and an ED50 of 40 μm is calculated with histamine as the stimulatory agent. When cyclic AMP formation is elicited by histamine : noradrenaline a significant effect of diazepam is seen at 10 μm and an ED50 of 16 μm is obtained. These results lend support to the hypothesis that the psychotropic action of the benzodiazepines may, at least in part, involve the cyclic AMP generating systems of the central nervous system.
INFLUENCE OF EARLY VISUAL DEPRIVATION ON REGIONAL ACTIVITY OF BRAIN ATPases IN DEVELOPING RATS1
Authors: Meisami E. , Timiras P. S.
Published: October 2006

The effects of light deprivation from birth to 40 days of age on the development of Na‐K‐ATPase and Mg‐ATPase activity, enzymes significantly involved in cerebral energy exchange, ion transport, and synaptic function, were investigated in visual and non‐visual brain areas of the rat. Although both enzymes generally showed a progressive depression with age in light‐deprived rats, Na‐K‐ATPase was more depressed than Mg‐ATPase, and significant effects were confined to the superior colliculi, visual cortex, frontal cortex and hypothalamus. A disparate developmental pattern was evidenced in Na‐K‐ATPase activity in the visual cortex, where it was higher than control values at day 10 but lower by day 40, and in the hypothalamus, where it was lower on days 10 and 25 but significantly higher on day 40. The depression of Mg‐ATPase in the hypothalamus of light‐deprived rats at all ages and the activation of Na‐K‐ATPase in this structure is interpreted to mean that discrete alterations may have occurred in neurosecretory functions of the hypothalamus, known to be responsive to light. Transferring dark‐reared animals to normal light‐cycle conditions at day 25 affected only Mg‐ATPase in the visual cortex and Na‐K‐ATPase in the hypothalamus, both enzymes showing a significant increase by day 40 over values in continually light‐deprived animals. These findings confirm that early light deprivation is associated with important biochemical and neuroendocrine changes that persist into adulthood.
PROTEIN AND PEPTIDE HYDROLASES OF THE RAT HYPOTHALAMUS AND PITUITARY
Authors: Marks N. , Galoyan A. , Grynbaum Alice , Lajtha A.
Published: October 2006

Peptide and peptidyl‐peptide hydrolase activities were measured in the cerebral cortex, adenoand neurohypophysis, anterior and posterior regions of the hypothalamus to assess regional differences in peptide hormone turnover. In general all enzyme activities were higher in the pituitary except for the monoacyl arylamidase which was lower, and neutral proteinase which was distributed more evenly in all regions. Of the enzymes measured the highest activities occurred in the presence of the di‐ and tripeptide substrates (aminopeptidases); this activity was some 20‐60‐fold higher than the acid and neutral proteinases. Comparison of the peptide‐amide substrates revealed the highest activity with the monoacyl derivative which was five‐fold higher than the dipeptidyl, and 50‐fold higher than the tripeptidyl (hormonal) factor Pro‐Leu‐Gly. NH2. Analysis of the breakdown products of the hormonal factor indicated inactivation by N‐terminal release of Pro, Leu with Gly. NH2 as the final product. Regional differences in enzyme content in neurosecretory areas suggest that this plays a role in the turnover of specific hormones.
EFFECTS OF ETHANOL ON SEROTONIN METABOLISM IN BRAIN
Authors: Tabakoff B. , Boggan W. O.
Published: October 2006

The effect of ethanol on serotonin metabolism in brains of mice was determined both after a single injection and ‘chronic’ administration of ethanol. Behavioral effects were also monitored.‘Chronic’ administration of ethanol by inhalation to mice resulted in an increased susceptibility to Metrazole induced seizures. This susceptibility was evident for 48 h after ‘withdrawal’ of mice from ethanol chambers. No differences in brain 5‐HT levels between control and ethanol treated mice were evident during withdrawal. However, a significant elevation in brain 5‐HIAA levels was noted during this period. Short lived increases in brain 5‐HIAA levels were also noted after a single injection of ethanol. Ethanol treatment produced no significant changes in the activity of brain MAO, aldehyde dehydrogenase, or aldehyde reductase. Other mechanisms for ethanol induced increases in brain 5‐HIAA are discussed.
REGIONAL DISTRIBUTION OF HOMOCARNOSINE AND OTHER NINHYDRIN‐POSITIVE SUBSTANCES IN BRAINS OF MALNOURISHED MONKEYS1
Authors: Enwonwu C. O. , Worthington Bonnie S.
Published: October 2006

—Eight male monkeys (Macaca nemestrina) aged 6–9 months were divided into two groups and fed either an adequate protein diet (20% casein) or a protein deficient diet (2% casein). After 3‐ 5 months of receiving the low protein diet, the malnourished monkeys showed extensive fatty metamorphosis of the liver cells, distorted patterns of plasma and hepatic free amino acid pools, and other features consistent with the diagnosis of protein‐calorie malnutrition. Examination of the cerebrum, cerebellum and brain stem in the malnourished animals revealed profound accumulation of 3‐methylhistidine, histidine and homocarnosine in all three regions. For histidine, the cerebral, cerebellar and brain stem levels in the protein deficient animals increased by 145, 104 and 101 per cent over levels observed in corresponding regions of the brain in well‐fed monkeys. Similarly, there were significant elevations in homocarnosine contents of the cerebrum (+ 99 per cent), cerebellum (+ 140 per cent) and brain stem (+ 146 per cent) in comparison to levels in control animals. In contrast, the levels of valine, serine and aspartic acid were markedly reduced in all three brain areas in the malnourished animals. Protein‐calorie deficiency also produced reductions in the brain levels of taurine, glutamic acid, isoleucine, leucine and threonine which varied in magnitude in the three major regions of the brain examined. These biochemical alterations which may in part underlie some of the psychomotor changes often observed in protein‐calorie malnutrition, were discussed not only in relation to the role of amino acids as precursors for the synthesis of neuroregulatory substances but also with due regard to the possibility that some of these ninhydrin‐positive substances such as GABA, homocarnosine, glycine and the dicarboxylic amino acids may possess neuroexcitatory or inhibitory properties in various parts of the central nervous system.
PURIFICATION AND PROPERTIES OF CHOLINE ACETYLTRANSFERASE FROM THE NERVOUS SYSTEM OF DIFFERENT INVERTEBRATES
Authors: Emson P. C. , Malthe‐Sosrenssen D. , Fonnum F.
Published: October 2006

—Choline acetyltransferase has been purified from three invertebrate species, namely snail (Helix aspersa), cockroach (Periplaneta americana) and horse shoe crab (Limulus polyphemus.) All three enzymes followed a Theorell‐Chance enzyme mechanism with a sequential addition of the substrates. All three enzymes were activated by sodium and potassium chloride and inhibited by high concentrations of magnesium or calcium chloride. The apparent Km for choline and acetyl‐CoA was for snail: Kmch= 370 μm,KmAcetyl‐CoA= 51μm; cockroach:KmCh= 550 μm, KmAcely‐CoA= 16 μm horse shoe crab:KmCn= 2700 μm KmAcctyl‐coA= 68 μm

CoA inhibited the enzymes competitively with respect to acetyl‐CoA and non‐competitively with respect to choline. Acetylcholine inhibited the enzymes competitively with respect to choline and non‐competitively with respect to acetyl‐CoA. All the enzymes were inhibited strongly by 5,5′‐dithiobis (2‐nitrobenzoate), iodoacetate, acryloylcholine, chloracetylcholine and 3‐bromacetonyltrimethyl‐ammonium. The enzymes were only weakly inhibited by the styrylpyridine derivatives. The isoelectric points were 5.3 and 5.0 for the horse shoe crab and cockroach enzymes respectively. All three enzymes showed low affinity for a cation‐exchanger (CM‐Sephadex).
ON THE MECHANISM OF STIMULATION OF AMP‐AMINOHYDROLASE ACTIVITY BY HEXOKINASE IN BRAIN TISSUE
Authors: Haroutunian A. V. , Buniatian H. Ch.
Published: October 2006

—A hexokinase has been isolated from brain tissue on Sephadex G‐100 and DEAE cellulose which is similar to yeast enzyme in stimulating the AMP‐aminohydrolase activity of rat brain soluble fractions. This effect of hexokinase is influenced neither by N‐acetyl‐glucosamine nor noradrenaline. An isoenzyme of hexokinase isolated from brain tissue on DEAE cellulose, having properties similar to that of the muscle enzyme, has no effect on AMP‐aminohydrolase activity. The activating effect of yeast hexokinase is not due to its oligomeric structure. Enzyme subunits obtained by the treatment of native yeast enzyme by urea also activate AMP‐aminohydrolase of rat brain soluble fractions.
ASSOCIATION OF AXONALLY TRANSPORTED PROTEINS WITH GOLDFISH BRAIN MYELIN FRACTIONS
Authors: Elam J. S.
Published: October 2006

—The presence of rapidly transported axonal proteins in purified preparations of myelin has been investigated in the goldfish visual system. Fish were injected intraocularly with 3H proline and contralateral optic tecta were pooled 8–12 h later for purification of myelin. Three purification procedures were employed using continuous and discontinuous gradients of sucrose and continuous gradients of CsCl. All of the myelin preparations were found to have physical, chemical and enzymatic properties attributable to relatively pure preparations of myelin. The goldfish myelin differed from mammalian preparations in having a slightly lower density and in containing an additional major protein of approx. 45,000 mol. wt. All of the myelin preparations retained relatively high levels of axonally transported radioactivity with specific radioactivities which ranged from 70 to 80 per cent of that of the whole tectal homogenate. Acrylamide gel analysis showed the myelin‐associated radioactivity to be confined to the higher molecular weight proteins with very little radioactivity associated with basic protein or proteolipid protein. Both the axonally transported radioactivity and the group of higher molecular weight proteins were found to be more concentrated in a myelin subfraction of relatively high density than in a subfraction of low density. The possible significance of the association of axonally transported proteins with myelin is discussed.
CHANGES IN CARBOHYDRATE SUBSTRATES, AMINO ACIDS AND AMMONIA IN THE BRAIN DURING INSULIN‐INDUCED HYPOGLYCEMIA
Authors: Lewis L. D. , Ljunggren B. , Norberg K. , Siesjö B. K.
Published: October 2006

—The influence of insulin‐induced hypoglycemia upon carbohydrate substrates, amino acids and ammonia in the brain was studied in lightly anaesthetized rats, and the changes observed were related to the blood glucose concentration and to the EEG. Calculations from glucose concentrations in tissue, CSF and blood indicated the presence of appreciable amounts of free intracellular glucose at blood glucose concentrations above 3 μmol/g. When the blood glucose concentration fell below 3 μmol/g, there was no calculated intracellular glucose and decreases in the concentrations of glycogen, G‐6‐P, pyruvate, lactate and of citric acid cycle intermediates were observed. At blood glucose levels of below 1 μmol/g the tissue was virtually depleted of glycogen, G‐6‐P, pyruvate and lactate.

When the blood glucose concentration was reduced below about 2·5 μmol/g there were progressive increases in aspartate and progressive decreases in alanine, GABA, glutamine and glutamate, and at blood glucose concentrations below 2 μmol/g the ammonia concentration increased. It is suggested that most of the changes observed can be explained as a result of a decreased availability of pyruvate and of NADH. The decrease in the concentration of free NADH was reflected in reductions of the lactate/pyruvate and malate/oxaloacetate ratios at an unchanged intracellular pH.

Slow wave activity appeared in the EEG when the hypoglycemia gave rise to reduction of the intracellular glucose concentration to zero. Convulsive activity continued until carbohydrate stores in the form of glycogen and G‐6‐P were depleted. When this occurred the EEG became isoelectric. In all convulsive animals the concentration of the nervous system activity inhibitor, GABA, was decreased and stimulant, aspartate, was increased.
THE EFFECT OF γ‐AMINOBUTYRIC ACID ON BRAIN MITOCHONDRIAL ATP SYNTHESIS1
Authors: Lee L.‐W. , Liao C.‐L. , Yatsu F. M.
Published: October 2006

—Rat brain mitochondrial ATP synthesis was studied by measuring labeled orthophosphate incorporation into ADP to form ATP. GABA stimulates ATP synthesis, and this effect requires glutamate since with GABA alone little ATP is formed. The significance of this effect by GABA is unclear, but the mechanism may relate to induction of conformational change or chelation of cation.
INCREASED CONCENTRATIONS OF ACIDIC METABOLITES OF DOPAMINE IN THE SUPERIOR CERVICAL GANGLION FOLLOWING PREGANGLIONIC STIMULATION IN VIVO
Authors: Pearson J. D. M. , Sharman D. F.
Published: October 2006

—Evidence is presented for the presence of two acidic metabolites of dopamine, 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the sympathetic ganglia of some mammalian species other than ruminants. In the pig, electrical stimulation of the preganglionic nerves to the superior cervical ganglion results in a mean increase of 78 per cent in the concentration of HVA and a mean increase of 372 per cent in the concentration of DOPAC in this sympathetic ganglion. These results can be interpreted as further evidence for the involvement of dopamine in transmission at sympathetic ganglia.
POLYACRYLAMIDE GEL ELECTROPHORESIS OF RAT BRAIN ACETYLCHOLINESTERASE: ISOENZYMES OF NORMAL RAT BRAIN1
Authors: Vijayan V. K. , Brownson R. H.
Published: October 2006

Abstract— Triton‐solubilized acetylcholinesterase (EC 3.1.1.7) of rat brain was submitted to vertical flatbed polyacrylamide gel electrophoresis. Three anodally migrating isoenzyme zones with low relative mobilities could be resolved, each of which on quantitative densitometry appeared to consist of more than one subzone. More than 50 per cent of the total AChE activity was exhibited by the isoenzyme zone closest to the origin (isoenzyme zone 3).

Regional differences in AChE isoenzyme activity were quantitative only with the caudate‐putamen complex, midbrain, pons and medulla oblongata exhibiting relatively high content of the three isoenzymes and the cerebral cortex and olfactory bulb possessing weak isoenzyme activities. Intermediate levels of isoenzyme activities were observed in the cerebellum and hippocampus. In all areas examined, the relative percentage values for each isoenzyme remained constant. AChE isoenzymes from the forebrain, brain stem and cerebellum of 15‐ and 30‐day‐old rats appeared to have identical patterns. In brain stem, no quantitative differences could be detected in the isoenzyme activities between 15 and 30 days of age. At both ages, the isoenzymes of male and female rats did not show any qualitative differences.

The single cholinesterase (EC 3.1.1.8) isoenzyme which could be identified in brain stem supernatants of 30‐day‐old rats was weakly reactive and appeared to have the same relative mobility as the major acetylcholinesterase zone, zone 3.

Acetylcholinesterase isoenzymes failed to demonstrate any differential response toward varying concentrations of inhibitors and to changes in pH. While there were basic similarities in the acetylcholinesterase and cholinesterase isoenzyme patterns of brain, serum, liver, skeletal muscle and intestine, brain alone exhibited a marked preponderance of the acetylcholinesterase isoenzyme zone 3.
GUANYL CYCLASE IN CHICK EMBRYO BRAIN CELL CULTURES: EVIDENCE OF NEURONAL LOCALIZATION
Authors: Goridis C. , Massarelli R. , Sensenbrenner M. , Mandel P.
Published: October 2006

Abstract— Guanyl cyclase activity was studied in dissociated chick embryo brain cell cultures presenting different ratios of neuronal to glial elements. The cultures containing neurons in substantial numbers always had higher guanyl cyclase activities than those consisting mainly of glial cells. No guanyl cyclase activity could be found in cultures made up of pure glial or meningeal cells. These results provide further evidence for our conclusion based on subcellular fractionation studies (Goridis & Morgan, 1973), that brain guanyl cyclase might be overwhelmingly concentrated in neurons. Guanyl cyclase activity of chick embryo cerebral hemispheres increased sixfold between day 12 and day 16 after fertilization; an increase, though of much smaller magnitude, was also seen in cultured cells of the same age.
ON THE RELATIONSHIP OF BRAIN FILAMENTS TO MICROTUBULES1
Authors: Johnson Linda S. , Sinex F. Marott
Published: October 2006

Abstract— A method has been developed for the isolation of a previously undescribed fibrous protein from rat brain. The newly isolated material consists of bundles of tightly packed 70‐80 Å diameter filaments. Based on studies employing degenerated rat optic nerve, it is proposed that these filaments correspond to the well‐described astrocyte filaments observed in sectioned preparations of mammalian brain. The purified filaments are stable over a wide temperature range, are not disrupted by colchicine, and exhibit limited solubility in the absence of denaturants or detergents. In neutral SDS‐polyacrylamide gel electrophoresis, the filament protein runs as a single band with an apparent molecular weight of 57,000 daltons. This preparation also migrates as a single band in alkaline urea gels, and as a well‐resolved doublet on discontinuous SDS‐urea gels. In all three electrophoretic systems, the filament subunits co‐migrate with rat brain tubulin. Comparative peptide maps of the filament subunits and tubulin indicate a large degree of homology. Our results suggest that microtubules and astrocyte filaments are composed of the same or very similar protein subunits.
THE EFFECTS OF LITHIUM ON HIGH ENERGY PHOSPHATE AND GLUCOSE LEVELS IN THE RAT SUPERIOR CERVICAL GANGLION1
Authors: Organisciak D. T. , Klingman J. D.
Published: October 2006

Abstract— The effects of acute treatment with lithium ion (25 mm) on the levels of ATP, phosphocreatine and glucose were measured in an in vitro preparation of rat superior cervical ganglion. Similar analyses were performed on ganglia from rats fed a chronic lithium diet (0.5 mm). Ganglia were excised and de‐sheathed, then stimulated (5 Hz) or rested for 20, 40 or 80 min in normal or lithium‐containing Krebs‐Ringer bathing solutions. Following freeze drying, enzymatic pyridine nucleotide methods were used to measure fluorometrically ATP, phosphocreatine and glucose on portions of a ganglionic perchloric acid extract.

After 20 min of incubation, normal ganglionic contents of ATP and phosphocreatine were higher than the initial zero time levels. Incubation for periods longer than 20 min resulted in ATP and phosphocreatine levels which were lower than those at zero time. Stimulation of normal ganglia caused a decrease in the contents of high‐energy phosphates relative to those in the resting state. Except for the 20 min time period the ATP levels were lower than normal in ganglia from rats chronically fed lithium. Levels of ATP and phosphocreatine in ganglia acutely exposed to lithium were significantly lower than in both normal ganglia and ganglia from chronically‐treated rats. In comparison to normal ganglia, significantly lower levels of glucose were found only for stimulated ganglia acutely exposed to lithium.
PROTEIN SYNTHESIS BY CEREBRAL POLYSOMES PRETREATED WITH PUROMYCIN
Authors: Murthy M. R. V. , Roux Huguette
Published: October 2006

Abstract— Polysomes prepared from rat cerebral microsomes, following preincubation with a high concentration of puromycin (2.5 mM) in the presence of rat liver soluble enzymes, were very similar to normal polysomes in yield, A 260nm:A 280nm ratio and in absorbance profile on sucrose density gradients. However, the capacity for amino acid incorporation was inhibited by more than 50 per cent by puromycin treatment. The extent of inhibition far exceeded what could be expected from the amount of residual puromycin bound to polysomes, suggesting that some essential step in polypeptide synthesis was damaged. An examination of the labelled polypeptides, using sucrose density gradient centrifugation, showed that most of the new chains synthesized by puromycin‐polysomes were released into solution. However, small amounts of polypeptides of high specific radioactivity were distributed among the polysomal aggregates. In contrast to normal polysomes, the specific radioactivity of puromycin polysomes was the highest in aggregates of six or more ribosomes and declined sharply at the levels of trimers and dimers. It is suggested that cerebral polysomes pretreated with puromycin become defective in the termination mechanism with the consequence that even though they are capable of moving at least short distances on the messenger RNA and of releasing the polypeptide chains formed, a concomittant release of monomeric ribosomes is obstructed. This may result in the‘clogging’of the terminus of the mRNA, thus blocking further polypeptide synthesis.
INHIBITION OF THE BIOCHEMICAL AND MORPHOLOGICAL MATURATION OF ADRENERGIC NEURONS BY NICOTINIC RECEPTOR BLOCKADE
Authors: Black I. B. , Geen S. C.
Published: October 2006

Abstract— The developmental increases of tyrosine hydroxylase, dopa decarboxylase and doparnine‐β‐hydroxylase activities in neonatal mouse superior cervical ganglion were prevented by administration of the ganglionic blocking agent chlorisondamine. In addition, ganglionic blockade prevented the normal post‐natal increase in ganglion volume and neuron numbers. Inhibition of development followed nicotinic‐receptor blockade, but not muscarinic blockade with atropine.
CONTROL OF THE REDOX STATE OF THE PYRIDINE NUCLEOTIDES IN THE RAT CEREBRAL CORTEX. EFFECT OF ELECTROSHOCK‐INDUCED SEIZURES
Authors: Howse D. C. , Duffy T. E.
Published: October 2006

—The concentrations of most of the intermediates of glycolysis and of the tricarboxylic acid cycle were determined in the cerebral cortex of rats, frozen 10 s after the induction of a generalized seizure by electroshock. The apparent equilibrium constant for the combined glyceraldehyde‐3‐phosphate dehydrogenase, 3‐phosphoglycerate kinase and lactic dehydrogenase reactions, i.e. Kapp= [Lactate] [3‐Phosphoglycerate] [ATP]/[Pyruvate] [Glyceraldehyde‐3‐phosphate] [ADP] [HPO24], was evaluated and found to be similar to the value reported for the in vitro system at pH 7. During an estimated 4–5‐fold increase in glycolytic flux imposed by the seizure, this system remained close to equilibrium. In control cortex the components of the aldolase reaction were deviated 80‐fold from equilibrium but shifted slightly toward equilibrium during the seizure. The components of the aspartate aminotransferase reaction were maintained in equilibrium in both the control and the seizure states.

Of 4 reactions used to assess the cytoplasmic and mitochondrial redox states, only the lactic dehydrogenase reaction was considered reliable in the acutely changing situation of the seizure, and yielded a calculated decrease in the cytoplasmic [NAD+]/[NADH] ratio. This change, coupled with an observed decrease in the [ATP]/[ADP] [HPO24] ratio during the seizure, supports the concept that in brain, as in liver (Krebs & Veech, 1969), the phosphate potential determines the redox state of the tissue.
PURIFICATION OF RAT BRAIN CHOLINE ACETYLTRANSFERASE AND AN ESTIMATION OF ITS HALF‐LIFE
Authors: Wenthold R. J. , Mahler H. R.
Published: October 2006

—Acetyl‐CoA:choline‐O‐acetyltransferase (ChAc, EC 2.3.1.6) was purified from rat cerebral cortex and its half‐life determined. The molecular weight of the enzyme under non‐denaturing conditions was estimated by gel filtration to be in the range of 60,000–65,000. On SDS acrylamide gels, the purified enzyme migrated as a single band with a molecular weight estimated as 62,000. The turnover rate of ChAc in the mature rat was determined by the double label method, employing l‐[1‐14C]leucine and l‐[4,5‐3H]leucine. Its half‐life under steady‐state conditions was estimated to be 5.2 days. As a control, tubulin was isolated from the same preparation and its half‐life measured. Under these conditions tubulin exhibited a half‐life of 3.8 days.
REGIONAL γ‐AMINOBUTYRIC ACID LEVELS IN RAT BRAIN DETERMINED AFTER MICROWAVE FIXATION
Authors: Balcom G. J. , Lenox R. H. , Meyerhoff J. L.
Published: October 2006

—GABA levels in rat whole brain were compared following three methods of sacrifice: rapid microwave fixation, decapitation into liquid nitrogen, and decapitation at 20°C. Levels were shown to be identical in animals sacrificed by microwave fixation and decapitation into liquid nitrogen. In contrast, rats decapitated at 20°C had 18 per cent higher GABA levels when determined immediately post‐mortem and 48 per cent higher levels after 30 min at 20°C. Microwave treatment prevented these post‐mortem increases. The increase in GABA after decapitation at 20°C was even greater in hypothalamus than in whole brain.

A comparison of 3 GABA extraction methods following microwave fixation demonstrated that sodium acetate was 88 per cent as effective as 80 per cent ethanol and more effective than 0·5 n‐perchloric acid in extracting GABA.

Fifteen brain regions were dissected from microwave‐treated brains and the GABA levels determined.
EFFECTS OF DI‐ISOPROPYLFLUOROPHOSPHATE ON THE METABOLISM OF CHOLINE AND PHOSPHATIDYLCHOLINE IN RAT BRAIN
Authors: Dross K.
Published: October 2006

—The subcutaneous administration of 2·0 mg DFP per kg to rats causes a diminution in the lysophosphatidylcholine content in the brain, which is followed by a decrease of glycerylphosphorylcholine concentration and by a reduced post mortem choline increase. This supports the hypothesis that a post mortem increase in choline is due to phosphatidylcholine breakdown. Since the amount of phosphatidylcholine in brains of di‐isopropylfluorophosphate‐treated rats increases, it is concluded that phospholipase A is inhibited by di‐isopropylfluorophosphate, which corresponds to findings of other authors in vitro. The activity of glycerylphosphorylcholine diesterase (EC 3.1.4.2) is not altered.
SOLUBLE AND PARTICLE‐BOUND ACETYLCHOLINESTERASE AND ITS ISOENZYMES IN PERIPHERAL NERVES
Authors: Skangiel‐Kramska Jolanta , Niemierko Stella
Published: October 2006

Abstract— The distribution of AChE (EC 3.1.1.7) in soluble and particulate fractions of the peripheral nerves of dogs, cats, rabbits and frogs was examined. About 20–30% of the total AChE activity was found in the supernatant fluid after centrifugation (100,000 g for 90 min) of iso‐osmotic sucrose homogenates. The effect of different media on the extent of solubilization of the enzyme was studied and Triton X‐100 (0.2%) was found to be the most effective. The electrophoretic pattern of AChE in peripheral nerves was also investigated. The 2–3 types of AChE observed previously were found in both particulate and soluble fractions, but the proportions of these forms were different. The most slowly migrating form of AChE is the most firmly bound to nerve membranes. A very small but consistent proportion (3%) of AChE escaped into the medium from surviving dog nerves kept in aerated Ringer solution. It was calculated that the possible contribution of blood AChE contained in the nerve is negligible. Electrophoretograms of AChE released during incubation into Ringer solution were similar in pattern to those found for the soluble fraction.
AMINO ACID TRANSPORT IN PERIPHERAL NERVE: ENERGY AND SODIUM DEPENDENCE
Authors: Wheeler D. D.
Published: October 2006

Abstract— The energy and sodium dependence of the several carrier‐mediated mechanisms for amino acid uptake have been studied in frog sciatic nerve. The different transport mechanisms are found to be variable in their dependence on sodium and metabolic energy. Saturable uptakes of lysine, phenylalanine and valine are relatively independent of the presence or absence of sodium in the incubation medium, indicating that uptakes by those mechanisms subserving basic, large neutral amino acids, and those amino acids containing aromatic or heterocyclic ring structures are largely sodium independent. Saturable uptakes of glutamic acid, proline, glycine and β‐alanine are considerably reduced in the absence of sodium; thus carrier mechanisms for uptake of acidic, small neutral amino acids, β‐alanine and proline are highly sodium dependent. The efficacies of several cations in substituting for sodium is variable; greatest inhibitions are found when potassium is used to replace sodium.

With the exception of proline, those mechanisms found to be sodium dependent are also found to be energy dependent, since they are inhibited by both DNP and lowered temperature. Although proline uptake is sodium dependent, proline uptake is stimulated by DNP and relatively insensitive to lowered temperature.
ATPase ACTIVITY OF NEUROBLASTOMA CELLS IN CULTURE
Authors: Ledig M. , Ciesielski‐Treska J. , Cam Y. , Montagnon D. , Mandel P.
Published: October 2006

—Neuroblastoma cells were cultured in the presence of fetal serum. When serum was omitted from the growth medium and also when dibutyryl cyclic AMP or insulin were added without omitting serum, there was a growth of neuron‐like processes which was in most cases accompanied by an increase in Na+‐K+ ‐ATPase activity, whereas Mg2+‐ATPase activity increased to a lesser extent. The increase in ATPase activities was related to cell density. When the ATPase activities were measured in the presence of 0·25 m‐sucrose or 1% deoxycholate the specific activities were decreased. There was no loss of activity during storage at –20°C for several days when 20% glycerol was added to the medium.
AXONAL TRANSPORT OF LABELLED PROTEINS IN SENSORY FIBRES OF RABBIT VAGUS NERVE IN VITRO
Authors: McLean W. G. , Frizell M. , Sjöstrand J.
Published: October 2006

—Rabbit vagus nerves and nodose ganglia were incubated in vitro for up to 24 h in two‐compartment chambers. After the introduction of [3H]leucine or [3H]fucose to the ganglion compartments a rapid anterograde axonal transport of labelled proteins or glycoproteins occurred at rates of 330 ± 44 mm/day and 336 ± 30 mm/day respectively. Accumulation of [3H]leucine‐labelled proteins proximal to a ligature on the nerve was unaffected by a delay of up to 6 h between removal of the nerve and labelling in vitro. Accumulation was prevented by inhibition of protein synthesis in the ganglion but not in the axon and was inhibited in a graded manner by colchicine.
SUBUNITS OF CHOLINE ACETYLTRANSFERASE (EC 2.3.1.6)
Authors: Chao L.‐P.
Published: October 2006

Abstract— The molecular weight of choline acetyltransferase is determined to be approx 87,000‐89,000 daltons. There are 808 amino acid residues per molecule of the enzyme with a calculated mol. wt of 89,300. Peptides of ChAc were studied after tryptic digestion, cyanogen bromide and BNPS‐skatole cleavages. The results of these studies suggest that the enzyme contains 6 identical subunits with 133 amino acid residues each and with a calculated molecular weight of 14,700 daltons for the monomer. This conclusion is supported by the fact that serine is the only amino terminal residue and alanine is the only carboxyl‐terminal group.