bluuebunny/crossref_metadata_2025 huggingface dataset:
HIGH AFFINITY AMINO ACID TRANSPORT BY FROG SPINAL CORD SLICES
Authors: Davidoff R. A. , Adair R.
Published: October 2006

Abstract—

The characteristics of amino acid uptake by frog spinal cord slices was studied by in vitro incubations in appropriate media. The uptake mechanisms exhibited saturation; kinetic analysis demonstrated 2 distinct systems for the influx of the possible neurotransmitters: GABA, glycine, L‐glutamic acid and L‐aspartic acid. One system showed a comparatively high substrate affinity (Km values, 10‐26 μM) while the other system had a lower affinity (Km, 0.4‐1.6 mM).‐Leucine, an amino acid presumably not a transmitter, was accumulated only by a low affinity mechanism (Km 1.6 mM). The process responsible for high affinity uptake had many of the properties of an active transport mechanism. These included temperature sensitivity, energy dependence, requirement for Na+ ions and inhibition by ouabain. GABA and glycine uptake was inhibited only by closely related amino acids or structural analogues. The influx of L‐glutamic acid was competitively inhibited by the presence of L‐aspartic acid in the medium; the converse was also demonstrated. Thus, the high affinity uptake system for possible transmitter amino acids in the frog spinal cord closely resembles that described for mammalian CNS tissue. These results are compatible with the assumption that GABA, glycine, L‐glutamic acid and L‐aspartic acid are neurotransmitters in the amphibian spinal cord.
THE P2 PROTEIN OF BOVINE ROOT MYELIN: PARTIAL CHEMICAL CHARACTERIZATION1
Authors: Brostoff S. W. , Sacks H. , DiPaola C.
Published: October 2006

Abstract—

The P2 protein of bovine root myelin has chemical characteristics which differentiate it from other myelin basic proteins. The tryptic peptide map of the bovine P2 protein is distinctly different from the map of either the rabbit PI protein or the bovine CNS myelin basic protein. The tryptic peptides of the P2 protein show no overlap in either map positions or amino acid content with the peptides of the CNS myelin basic protein. Analysis of the individual peptides in the P2 map accounted for all of the amino acids present in the analysis of the whole protein. The P2 protein has a blocked NH2‐terminus, lysine at its COOH‐terminus and no hexosamine. CD studies revealed that the P2 protein has a very stable β‐structure in aqueous solution at neutral or basic pH and retains much of this structure in acid and in 8 M urea. It is suggested that these structural properties are relevant to the dual role of the P2 protein as a membrane constituent and as an antigen.
EFFECT OF DELTA‐9‐TETRAHYDROCANNABINOL ADMINISTRATION ON THE LIPID CONSTITUENTS OF RAT BRAIN SUBCELLULAR FRACTIONS
Authors: Sarkar C. , Ghosh J. J.
Published: October 2006

Abstract—

An investigation on the effects of acute (10 mg/kg) and chronic (10 mg/kg for 15 days) treatment with Δ9‐THC administration by the intraperitoneal route, on the cholesterol, cerebroside and individual phospholipid contents in microsomal, synaptosomal, mitochodrial and myelin fractions from adult rat brain, is reported. The drug has been found to affect the different subcellular membranous lipid and phospholipid components in a characteristic manner.
NUCLEAR PROTEIN PATTERNS IN DEVELOPING AND ADULT BRAIN AND IN ETHYLNITROSOUREA‐INDUCED NEUROECTODERMAL TUMOURS OF THE RAT1,2
Authors: Biessmann H. , Rajewsky M. F.
Published: October 2006

Abstract—

In a comparative study, the patterns of histones and non‐histone proteins were analysed in the chromatin of foetal (18th day of gestation), 10‐day‐old, and adult BD IX‐rat brain, as well as in the chromatin of two ethylnitrosourea‐induced neuroectodermal tumours (TV1A1 and GV1A1) and the corresponding malignant cell culture lines TV1C1 and GV1C1. Separation of nuclear proteins at high resolution was obtained by electrophoresis in 15% and 10% polyacrylamide gels containing urea (2·5 m or 6·25 m). In spite of an overall similarity, significant quantitative and qualitative differences were observed between the respective non‐histone proteins banding patterns of normal brain and the neoplastic cells analysed. The non‐histone protein banding patterns of brain (∼40 different bands) at different stages of development revealed both quantitative differences and the presence of particular bands characteristic of foetal or adult brain, respectively. Both the‘foetal’and‘adult’non‐histone protein bands also appeared in the electrophoretograms of the neoplastic neuroectodermal cells.
EFFECT OF STIMULATION OF EXCITATORY NERVE TRACT ON RELEASE OF GLUTAMIC ACID FROM OLFACTORY CORTEX SLICES IN VITRO
Authors: Yamamoto C. , Matsui S.
Published: October 2006

Abstract— Thin sections prepared from the olfactory cortex of the guinea pig were incubated in a medium containing [14C]glutamate, and release of radioactive compounds and electrical activity were subsequently examined in the presence of l‐cysteate. The postsynaptic potential was almost completely suppressed in the medium containing l‐cysteate, whereas the presynaptic potential was unaffected. Repetitive stimulation of the excitatory input of the lateral olfactory tract enhanced release of radioactive glutamate. The facilitatory effect of lateral olfactory tract stimulation increased with increase in stimulus frequency and was dependent on calcium. Release of radioactive gluiamine was not enhanced by lateral olfactory tract stimulation. Phenobarbitone sodium markedly depressed both the postsynaptic potential and the effect of lateral olfactory tract stimulation on glutamate release. These results indicate that stimulation to the lateral olfactory tract enhances liberation of glutamate from the tract nerve terminals.
A RECOMBINATION ASSAY OF HIGH MOLECULAR WEIGHT NERVE GROWTH FACTOR PROTEIN COMPLEXES
Authors: Shine H. D. , Perez‐POLO J. R.
Published: October 2006

Abstract— The 7S Nerve Growth Factor (NGF) found in mouse is a protein composed of three dissimilar subunits designated α, γ, and β. Mouse NGF reversibly dissociates into its component subunits at pH values lower than 5 or greater than 8. The 7S protein complex is in fast equilibrium wiih the free subunits. A quantitative determination of 7S NGF based on the reversible dissociation of the molecule into its subunits is reported here. The basis for this procedure is the addition of [125I]α subunit which competes with the native alpha in the 7S complex. The level of NGF present in a sample can be measured in terms of the displacement of [125I]α from the α to the NGF position in a linear sucrose gradient. Measurements are sensitive to 3.5ng of NGF, linear, and specific for the NGF molecule. This exchange is unaffccted by competing unrelated growth factors and inhibiting enzymes. Its specificity was checked by the standard bioassay and by radioimmunoassay. In addition, the assay technique overrides masking by biological inhibitors and/or by the presence of antibodies directed against the IgG contaminant in murine 75 NGF.
PHOSPHORYLATION OF ENDOGENOUS PROTEINS IN MYELIN OF RAT BRAIN
Authors: Miyamoto E.
Published: October 2006

Abstract— The phosphorylation of endogenous proteins occurring in the myelin of rat brain was examined using the method of sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. Two myelin basic proteins and at least five more proteins were phosphorylated after incubation of myelin fraction in the presence of ATP + Mg2+. The apparent molecular weights of the proteins other than the myelin basic proteins were 120,000, 76,000, 60,000, 41,000 and 38,000, respectively. The proteins of mol wt 60,000. 41,000 and 38,000 were extracted by treatment with hydrochloric acid, whereas those of mol wt 120,000 and 76,000 were insoluble in hydrochloric acid and chloroform‐methanol. Folch‐Lees proteolipid protein was not found to be phosphorylated under the conditions studied. The endogenous phosphorylation of the proteins was not stimulated by adenosine 3′,5′‐monophosphate.
DEMONSTRATION D'UNE RELATION INVERSEMENT PROPORTIONNELLE ENTRE LA DOPAMINE ET LA SEROTONINE DANS CERTAINES STRUCTURES CEREBRALES: ASPECTS NEUROCHIMIQUE ET MORPHOLOGIQUE1
Authors: Roberge A. G. , Parent A. , Boulay M.
Published: October 2006

Résumée

Une diminution significative de la sérotonine dans toutes les structures du cerveau est démontrée chez le chat suìte à un traitement chronique à la p‐chlorophénylalanine (250 mg/kg i.p., 2 doses, à intervalles de 72 h). Les concentrations de noradrenaline ne sont pas affectées par un tel traitement. Par ailleurs, les concentrations de dopamine sont significativement augmentées dans le lobe piriforme, le septum, l'hypothalamus et le mésencéphale et normales dans. le néostriatum, le cortex frontal, le tuberculum olfactorium et le cervelet. Des chats porteurs d'une lésion sélective du noyau raphae dorsalis, sans atteinte des autres noyaux, démontrent une baisse significative de la sérotonine du néostriatum et du lobe piriforme. Comparativement aux chats traités à la p‐chlorophénylalanine, les chats lésés présentent une augmentation significative des concentrations de la dopamine du lobe piriforme alors que cells du néostriatum demeurent normales. Ces résultats permettent de dissocier les structures appartenant au système limbique des structures appartenent au système moteur extrapyramidal à la fois sur une base biochimique et morphologique. De plus, ces données suggèrent que. le rôle physiologique de la dopamine du système moteur extrapyramidal est fonctionnellement différent du rôle de la dopamine impliquée dans les structures du système limbique.

Cats treated chronically with p‐chlorophenylalanine (250 mg/kg, i.p., 2 doses, 72 h apart) demonstrate a significant decrease in serotonin concentrations in all structures within the brain. The noradrenaline level was not affected. Dopamine concentrations were however significantly increased in the piriform lobe, septum, hypothalamus and mesencephalon and unchanged in the neostriatum, frontal cortex, tuberculum olfactorium and cerebellum. In cats bearing a selective lesion of nucleus raphae dorsalis without involving other raphae nuclei, a significant decrease in serotonin was observed in the neostriatum and piriform lobe. Compared to p‐chlorophenylalanine treated cats, lesioned cats show a significant increase in dopamine content in the piriform lobe but not in the neostriatum. A single dose of p‐chlorophenylalanine (250 mg,kg, i.p.) as well as a selective lesion of nucleus raphae centralis superior caused a significant decrease in serotonin level without affecting dopamine concentration. Such findings allow differentiation of a group of structures belonging to the limbic system from those of the extrapyramidal motor system on a biochemical as well as on a morphological basis. Moreover these results suggest that dopamine in the nigrostriatal pathway has a different function from dopamine involved in the limbic system.
PRENATAL AND POSTNATAL PROTEIN RESTRICTION IN THE RAT: EFFECT ON SOME PARAMETERS RELATED TO BRAIN DEVELOPMENT, AND PROSPECTS FOR REHABILITATION1,2
Authors: Simons Sandra D. , Johnston Patricia V.
Published: October 2006

Abstract— From the third day of pregnancy rats were fed a diet containing either 7% casein (experimental) or 24% casein (control). During lactation the control dams were fed the 24% casein diet and the experimental dams a 12% casein diet. From 25 to 50 days of age the experimental and control progeny were fed diets containing 7 and 24% casein, respectively. Between 50 and 120 days both groups were fed a diet containing 24% crude protein. Several indications of brain maturation in two brain areas were examined at various stages of development. In addition to retardation of brain growth, protein restriction led to myelin of an immature composition at 25 and 50 days of age. The immature composition was indicated by a low plasmalogen content at 25 days and by a high phospholipid and low galactolipid and plasmalogen contents at 50 days of age. The activity of the myelin marker enzyme, 2′3′‐cyclic nucleotide 3′‐phosphohydrolase (CNP), was significantly lower in the brains (excluding the cerebella) of malnourished rats at 21, 30 and 50 days. At all ages except at 50 days the activity of CNP in the cerebellum was higher in protein‐deprived animals than in controls. The activity of glutamic acid decarboxylase (GAD) in the brains (excluding the cerebella) of protein‐deprived rats was significantly lower at 21, 25 and 30 days but not at 50 and 65 days of age. As indicated by brain/body ratios, myelin composition and GAD activity, nutritional rehabilitation led to almost complete recovery of brain maturity, but the activity of CNP remained lower in the experimental group after rehabilitation.
A RAPID METHOD FOR ASSAYING ENZYMES WHOSE SUBSTRATES AND PRODUCTS DIFFER BY CHARGE. APPLICATION TO BRAIN l‐GLUTAMATE DECARBOXYLASE
Authors: Chude Obi , Wu Jang‐Yen
Published: October 2006

Abstract— A simple, rapid, sensitive and economical assay technique has been developed for any enzyme whose substrate and product differ by charge. It is based on a combination of rapid vacuum filtration with an ion exchange resin. The technique has been successfully applied to brain glutamate decarboxylase.
ISOLATION AND CHARACTERIZATION OF PLASMA MEMBRANES FROM THE ADRENAL MEDULLA1
Authors: Wilson S. P. , Kirshner N.
Published: October 2006

Abstract– The isolation of a plasma membrane fraction from the bovine adrenal medulla and its characterization are described. The plasma membranes are enriched 13‐fold in AChE, a plasma membrane marker, and represent 0.7% of the homogenate membrane protein. The yield of these membranes is typically 10‐12% by the criterion of the percentage of total membrane bound AChE in the homogenate. The membranes were characterized as to their polypeptide, phospholipid and cholesterol content and compared with chromaffin vesicle, mitochondrial and microsomal membranes by these parameters.

Two enzymatic components of the plasma membranes, ATPase and adenylate cyclase, were also studied. Calcium ATPase activity is 2.5‐fold higher than magnesium ATPase activity, appears to be the result of a single enzyme, and is a genuine component of the plasma membranes. The magnesium stimulated activity appears to have at least two enzymatic components, one of which may be identical to the calcium ATPase.

Adenylate cyclase is a plasma membrane component, but may not be uniquely localized there, as it is rather unstable throughout the fractionation procedure. It is stimulated by GTP (0.7‐fold at 10−5M), GPP(NH)P (4.8‐fold at 10−5M) and sodium fluoride (4.6‐fold at 10−2M). It is refractory to stimulation by all other compounds tested.
7S NERVE GROWTH FACTOR PROTEIN IN THE GOLDEN HAMSTER
Authors: Shine H. D. , Perez‐Polo J. R.
Published: October 2006

Abstract– Levels of 7S nerve growth factor in various tissues of the Golden Hamster were measured using a new assay procedure. The assay consisted of labelling native 7S nerve growth factor by allowing an 125I‐labelled subunit ([125I]‐α) of 7S nerve growth factor to compete with the native a subunit. The presence of 7S nerve growth factor was noted in a wide variety of non‐neuronal and neuronal tissues. Levels of 7S nerve growth factor in the CNS decreased as the distance from the metencephalon increased both rostrally and caudally.
THE EFFECT OF l‐DOPA AND AN INHIBITOR OF PERIPHERAL DECARBOXYLATION ON GLUCOSE METABOLISM IN BRAIN1
Authors: Tyce Gertrude M.
Published: October 2006

Abstract– The effect of the administration of l‐DOPA plus an inhibitor of peripheral l‐aromatic amino acid decarboxylase (aromatic‐l‐amino‐acid carboxy‐lyase; EC 4.1.1.28) on the metabolism of glucose in brain was studied by administering [U‐I4C]glucose (20μCi) to three groups of rats: (1) rats that had been injected with l‐DOPA (200mg/kg) 28min earlier; (2) rats that had been similarly injected with l‐DOPA and also with N‐(d,l‐seryl)‐N′‐(2,3,4‐trihydroxybenzyl)hydrazine (50 mg/kg), an inhibitor of l‐aromatic amino acid decarboxylase, 30min before the l‐DOPA; and (3) appropriate controls. The flux of 14C from glucose in plasma to those amino acids that are in equilibrium with the tricarboxylic acid cycle intermediates was reduced by treatment with l‐DOPA and reduced further by treatment with l‐DOPA and the decarboxylase inhibitor. Concentrations of glucose in brain and in plasma were increased after treatment with l‐DOPA; these increases were attenuated if the inhibitor was given before the l‐DOPA. After treatment with l‐DOPA, there were decreases in the concentration of aspartate, tryptophan, and tyrosine in brain. After the administration of l‐DOPA and the decarboxylase inhibitor, the concentrations in brain of alanine, glutamate, tyrosine, and phenylalanine were greater, and the concentrations of aspartate, leucine, lysine, histidine, arginine, and tryptophan were less than in control rats.
FORMATION OF γ‐GLUTAMYLHISTAMINE FROM HISTAMINE IN RAT BRAIN
Authors: Konishi H. , Kakimoto Y.
Published: October 2006

Abstract– γ‐Glutamyl amides of histamine, serotonin and dopamine were formed from these amines by the transfer of the γ‐glutamyl moiety from γ‐glutamyl peptides in the presence of γ‐glutamyl transpeptidase. [I4C]Histamine was injected intraventricular into rats, and the formation of γ‐glutamyl‐[14C] histamine in the brain was confirmed by purification and identification with the authentic compound. The radioactivity was highest 30 min after the injection. The possible significance of γ‐glutamyl amides in nerve transmission is discussed.
TAURINE AND COBALT INDUCED EPILEPSY IN THE RAT: A BIOCHEMICAL AND ELECTROCORTICOGRAPHIC STUDY
Authors: Joseph M. H. , Emson P. C.
Published: October 2006

Abstract– The level of taurine around the epileptic focus induced by cobalt‐gelatine pellet implantation into rat brain was found to be reduced at 8‐11 days post‐operation, the time of maximal spike activity in the electrocorticogram. It returned towards normal at later times. This pattern was seen not only in the primary focus, but also to a lesser extent in the secondary focus in the contralateral cortex. Acute administration of taurine intraperitoneally or intraventricularly resulted in at most transient effects on epileptic spiking.

Chronic oral taurine elevated brain taurine in normal rats only after prolonged administration, but in cobalt‐treated rats it prevented the fall of taurine in the secondary focus, and reduced the extent and duration of the fall in the primary focus; nonetheless chronic oral or intraventricular administration failed to modify the development of spike activity. At 11 days after implantation, chronic oral taurine did not significantly reverse the falls in transmitter amino acids in the primary focus. It is concluded that taurine is ineffective in altering the development or expression of this type of cobalt‐induced epilepsy in the rat, in spite of adequate penetration to the brain. Possible reasons for the discrepancies with studies by other workers are discussed.
NEUROSECRETORY CELL PROTEIN METABOLISM IN THE LAND SNAIL,OTALA LACTEA
Authors: Loh Y. Peng , Barker J. L. , Gainer H.
Published: October 2006

—Protein synthesis in an identified molluscan neurosecretory cell of the land snail, Otala lactea was examined using three different types of polyacrylamide gel electrophoresis. Cells taken from active snails synthesized specific low molecular weight proteins while those from aestivated snails did not. Most of the newly synthesized low molecular weight proteins in the active snails were lost from the cell body when the preparations was chased for 19 h in label‐free enriched medium in the presence of anisomycin, an inhibitor of protein synthesis. If colchicine, a blocker of axonal transport, was included in the chase medium, the proteins present following a pulse were largely replaced by smaller molecular weight species. The results suggest that specific low molecular weight proteins are converted to smaller species and then transported from the cell body.
THE EFFECT OF HIGH CONCENTRATIONS OF HISTIDINE ON THE LEVEL OF OTHER AMINO ACIDS IN PLASMA AND BRAIN OF THE MATURE RAT
Authors: Typfield L. A. , Holton J. B.
Published: October 2006

—Changes in plasma and brain amino acids have been observed in adult rats 1 h after intraperitoneal injections of histidine and in others maintained on high histidine diets for 8 days. In the injection studies the compounds most consistently affected were the aromatic and branched chain amino acids and methionine. Reductions in their concentrations in the brain were explained by a competition with histidine for uptake into the tissue. There was little change in plasma amino acid levels. In the animals fed the highest concentration of histidine there was a generalized increase in brain, and a reduction in plasma, amino acid concentrations. A decrease in protein synthesis is postulated to explain this effect in brain.
NEUROBLASTOMA CELL ADENYLATE CYCLASE: DIRECT ACTIVATION BY ADENOSINE AND PROSTAGLANDINS1
Authors: Penit J. , Huot J. , Jard S.
Published: October 2006

—Adenylate cyclase activity of permeabilized neuroblastoma cells was measured by the conversion of [α32P]ATP into labelled cyclic AMP. Adenosine (10−6 ‐ 10−4m) induced a dose‐dependent increase in cyclic AMP formation. This effect could not be accounted for either by an adenosine‐induced inhibition of the phosphodiesterase activity present in the enzyme preparation, or by a direct conversion of adenosine into cyclic AMP. This indicates that the observed increase in cyclic AMP accumulation reflected an activation of adenylate cyclase. Adenosine is partially metabolized during the course of incubation with the enzyme preparation. However, none of the identified non‐phosphorylated adenosine metabolites were able to induce an adenylate cyclase activation. This suggests that adenosine itself is the stimulatory agent. The apparent Km of the adenylate cyclase for adenosine was 5 ± 10−6‐10−5m. Maximal activation represented 3‐4 times the basal value (10‐100 pmol cyclic AMP formed/10 min/mg protein). The adenosine effect was stereospecific, since structural analogues of adenosine were inactive. Adenosine increased the maximal velocity of the adenylate cyclase reaction. The stimulatory effect of adenosine was inhibited by theophylline. Prostaglandin PGE1 had a stimulatory effect much more pronounced than that of adenosine (6‐10‐fold the basal value at 10−6m). Dopamine and norepinephrine induced a slight adenylate cyclase activation which was not potentiated by adenosine. It is concluded that adenosine is able to activate directly neuroblastoma cell adenylate cyclase. It seems very likely that such a direct activation is also present in intact nervous tissue and account, at least partly, for the observed cyclic AMP accumulation in response to adenosine.
CHANGES IN ACYL GROUP COMPOSITION OF DIACYL‐GLYCEROPHOSPHORYLETHANOLAMINE, ALKENYLACYL‐GLYCEROPHOSPHORYLETHANOLAMINE AND DIACYL‐GLYCEROPHOSPHORYLCHOLINE IN MYELIN AND MICROSOMAL FRACTIONS OF MOUSE BRAIN DURING DEVELOPMENT
Authors: Sun G. Y. , Yau T. M.
Published: October 2006

—Age‐related changes in acyl group composition of diacyl‐glycerophosphorylethanolamine (GPE), alkenylacyl‐GPE and diacyl‐glycerophosphorylcholine (GPC) were examined in myelin and microsomal fractions of mouse brain during development. In general, the phosphoglycerides in the myelin fraction showed an increase in the proportions of 18:1 and 20:1 and a decrease in the proportions of 16:0, 20:4(n‐6) and 22:6(n‐3) with increasing age. These changes were especially obvious with the acyl groups of alkenylacyl‐GPE. The acyl group profiles of phosphoglycerides in the microsomal fraction were different from those in the myelin fraction. During development, there was an increase in 22:6 and a decrease in 20:4 in the phosphoglycerides of microsomes. These changes were especially obvious with the diacyl‐GPE. Starting from 2 weeks of age, there was also an increase in the proportions of 18:1 and 20:1 in alkenylacyl‐GPE in the microsomal fraction but this change was not as dramatic as that in the myelin fraction. In general, the acyl groups of diacyl‐GPC in both myelin and microsomal fractions showed only little age‐related changes as compared to the ethanolamine phosphoglycerides. Results suggest an induction in the synthesis of monoenoic fatty acids in brain during development. The monoenoic fatty acids synthesized during this period are rapidly and preferentially incorporated into the ethanolamine plasmalogen for further utilization in synthesis of the myelin membranes.
REGULATION OF PALMITIC ACID SYNTHESIS IN CULTURED GLIAL CELLS: EFFECTS OF GLUCOCORTICOID ON FATTY ACID SYNTHETASE, ACETYL‐CoA CARBOXYLASE, FATTY ACID AND STEROL SYNTHESIS1
Authors: Volpe J. J. , Marasa J. C.
Published: October 2006

Abstract— C‐6 glial cells in culture were utilized to define the role of glucocorticoid in the regulation of palmitic acid synthesis and the important lipogenic enzymes, fatty acid synthetase and acetyl‐CoA carboxylase. Particular emphasis was given to fatty acid synthetase which exhibited more than a 50% reduction in specific activity when cells were exposed to hydrocortisone (10 μg/ml) for 1 week. Coordinate changes in acetyl‐CoA carboxylase activity and in palmitic acid (and sterol) synthesis from acetate accompanied the alterations in fatty acid synthetase. Immunochemical techniques were utilized to show that the decrease in synthetase activity involved an alteration in enzyme content, not in catalytic efficiency. The changes in content of fatty acid synthetase were caused by alterations in enzyme synthesis. Glucocorticoids may regulate fatty acid synthetase in C‐6 glial cells by a mechanism similar to that suggested for adipose tissue. The inhibition of palmitic acid synthesis may be relevant to other effects of glucocorticoids on developing brain.
ANALYSIS OF RNA SYNTHESIZED BY AN ISOLATED RAT BRAIN SYNAPTOSOMAL FRACTION
Authors: England J. M. , Attardi G.
Published: October 2006

Abstract— A synaptosomal fraction derived from rat brain, when incubated in an appropriate medium. incorporates [5‐3H]uridine into RNA. On the basis of sedimentation analysis, RNA‐DNA hybridization and metabolic inhibitor studies, mitochondrial RNA species appear to be the major, if not sole, RNA products synthesized by the isolated synaptosomal fraction. Electronmicroscope autoradiographic analysis showed that about 50% of the incorporation of [5‐3H]uridine into RNA by this fraction occurs in the presynaptic endings. The capacity of mitochondrial RNA synthesis in isolated nerve endings declines as the age of the animal increases from 10 to 30 days, and by 60 days of age discrete mitochondrial RNA species are barely detectable.
RESPONSE OF RAT BRAIN INDOLES AND MOTOR ACTIVITY TO SHORT LIGHT‐DARK CYCLES1
Authors: Hanselma Georgiana , Borbély A. A.
Published: October 2006

Abstract—

Since the vigilance states of the rat can be largely controlled by one hour light‐one hour dark cycles, we investigated the effect of this photoperiod on the rat brain indoles and motor activity. Groups of 9 rats were killed 15‐20 min or 45‐50 min after the onset of the 1‐hour light or 1‐hour dark period. Serotonin (5HT) and 5‐hydroxyindoleacetic acid were determined fluorometrically in cortex, hypothalamus and brain stem. Tryptophan was determined fluorometrically in serum, cortex and hypothalamus. Cortical tryptophan was highest at the end of the dark period, whereas cortical 5‐HT and 5‐hydroxyindoleacetic. acid were highest at the beginning of the light period. Motor activity was high during darkness and low during light.

When the biochemical results were compared to the motor activity records of the individual animals, the decrease in motor activity at the onset of light correlated significantly with the cortical 5‐hydroxyin‐ doleacetic acid/5‐HT ratio in the animals killed at the beginning of the light period. The results indicate a rapid response of the cortical indoles to the onset of light and support the hypothesis that the induction of sleep is related to the brain indole metabolism.
UPTAKE OF α‐METHYL‐D‐GLUCOSIDE BY SYNAPTOSOMES FROM RAT BRAIN
Authors: Warfield Anna S. , Segal S.
Published: October 2006

Influx of α‐methylglucoside into synaptosomes prepared by differential and Ficoll density gradient centrifugation was studied to determine whether this sugar could be used as a model for glucose transport in nerve endings. The rate of uptake of a‐methylglucoside was linear over a wide range of substrate concentrations. Influx was only slightly inhibited (12–15%) in the presence of glucose, 2‐deoxyglncose, phloretin and 2,4‐dinitrophenol and was unaffected by galactose or phlorizin. Conver‐ sion of a‐methylglucoside to phosphorylated intermediates in synaptosomes was negligible. The data are consislent with the influx of a‐methylglucoside being primarily a diffusion process or being mediated by a system with an extremely high Km. However, it is possible that a small portion of the sugar may be transported by the low affinity glucose transport system. The results indicate that a‐methylgluco‐ side is not a good model for glucose transport in synaptosomes as it is in other tissues.
CHANGES IN THE GABA SYSTEM IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS‐INDUCED PARALYSIS
Authors: Gottesfeld Zehava , Teitelbaum Dvora , Webb Cynthia , Arnon Ruth
Published: October 2006

Abstract— The content of γ‐aminobutyric acid (GABA), but not glutamate, and the uptake of [3H]GABA by synaptosomes was reduced in the lumbar cord of guinea pigs during experimental allergic encephalomyelitis (EAE)‐induced hind limb paralysis. The decrease in glutamate decarboxylase (GAD) activity in the dorsal and ventral parts of the cord was confined to the lumbar region, and appeared before the onset of motor dysfunction. No change in activity was found in the thoracic cord, motor cortex, cerebellum or striatum. GAD activity remained unchanged in animals which were EAE‐sensitized but did not develop the clinical symptoms. Choline acetyltransferase activity did not change in the cord during paralysis.
THE SUBCELLULAR DISTRIBUTION OF CARBONIC ANHYDRASE IN HOMOGENATES OF PERFUSED RAT BRAIN
Authors: Yandrasitz J. R. , Ernst S. A. , Salganicoff L.
Published: October 2006

Abstract— The distribution of carbonic anhydrase was examined in subcellular fractions of perfused rat brain and compared with those of markers for cytosol (lactic dehydrogenase), mitochondrial matrix (glutamic dehydrogenase), and mitochondrial membranes (succinic dehydrogenase). About half of the total carbonic anhydrase was found in particulate fractions, with the greatest part of this in the crude mitochondrial fraction. This fraction was separated into its components on a discontinuous sucrose gradient either as such or after isotonic mechanical disruption with a French pressure cell, and the resultant fractions were characterized by electron microscopy and by assay of marker enzymes.

Carbonic anhydrase was solubilized by mechanical disruption, but not to the same extent as lactic dehydrogenase. The highest specific activity for carbonic anhydrase was found in the myelin fraction of the gradient. A mitochondrial locus for carbonic anhydrase is unlikely, but the presence of the enzyme in synaptosomes remains in question.

Addition of soluble carbonic anhydrase did not significantly increase the activity of particulate fractions. Treatment of particulate fractions with detergent was necessary to reveal latent activity; this procedure resulted in a more than ten‐fold increase in the measurable carbonic anhydrase activity of myelin fragments.
NEUROCHEMICAL CORRELATES OF BEHAVIOR
Authors: Smith J. E. , Hingtgen J. N. , McBride W. J. , Aprison M. H.
Published: October 2006

Abstract— Pigeons working on a multiple fixed ratio 50, fixed interval 10 schedule for food reinforcement were killed at 0, 50, 90, 150 and 240 min after an i.m. injection of 300mg/kg l‐tryptophan. The levels of tryptophan, 5‐hydroxytryptophan, 5‐hydroxytryptamine, 5‐hydroxyindole acetic acid, tyrosine, dopamine and norepinephrine were concurrently measured in crude nerve ending fractions (P2) isolated from the telencephalon, diencephalon plus mesencephalon and pons plus medulla‐oblongata of each pigeon. Increases in 5‐hydroxytryptamine levels in the nerve ending fraction from the telencephalon were correlated with the onset of the decreased response rates, whereas a return to baseline responding was correlated with a return to normal serotonin levels in this fraction. Changes in dopamine or norepinephrine were not related to the onset of or recovery from the decreased response rate. One group of pigeons were found which did not display any behavioral disruption even though each had received an injection of l‐tryptophan; the content of 5‐hydroxytryptophan, 5‐hydroxytryptamine and 5‐hydroxyindoleacetic acid in the nerve ending fraction isolated from the telencephalon of these birds did not differ from control values.
DISTRIBUTION AND REGULATION OF CYCLIC NUCLEOTIDE LEVELS IN CEREBELLUM, IN VIVO1
Authors: Rubin E. H. , Ferrendelli J. A.
Published: October 2006

Abstract— In mouse cerebellum, in vivo. cyclic GMP levels are 7 pmol/mg protein in the vermis and 40% lower in the hemispheres, whereas cyclic AMP levels are 7 9 pmol/mg protein in both regions. In the vermis. most of the cyclic GMP is contained in the molecular layer; cyclic AMP levels are highest in the granular layer. Amphetamine, harmaline. pentylenetetrazol and physical shaking elevate, and diazepam and reserpine depress levels of cyclic GMP in both vermis and hemispheres. Oxotremorine and atropine, respectively, increase and decrease cyclic GMP levels only in vermis. Regardless of the agent used, most of the change (67 89%) in cyclic GMP levels occurs in the molecular layer of the vermis; the remainder occurs in the granular layer. Of the drugs tested, only pentylenetetrazol affects cyclic AMP levels, and this drug increases cyclic AMP levels in both vermis and hemispheres and causes equal elevations in the molecular and granular layers of the vermis. In incubated slices of mouse cerebellum, none of the drugs produces changes in cyclic nucleotide levels which are similar to those in vivo. These data indicate that many drugs and conditions that alter cyclic GMP levels in cerebellum act via a common, but indirect, process.

We suggest that cyclic GMP levels in cerebellum are regulated by the activity of both the climbing fiber and mossy fiber cerebellar afferent systems. Increased activity in these afferent pathways causes elevation of cyclic GMP levels in Purkinje cells and perhaps in other cells; decreased activity leads to depressed cyclic GMP levels.
CONCENTRATIONS OF ENERGY METABOLITES AND CYCLIC NUCLEOTIDES DURING AND AFTER BILATERAL ISCHEMIA IN THE GERBIL CEREBRAL CORTEX
Authors: Kobayashi M. , Lust W. D. , Passonneau Janet V.
Published: October 2006

Abstract— The concentrations of metabolites which reflect energy production or use (P‐creatine, ATP. ADP. 5′AMP, glucose, glycogen and lactate) and cyclic nucleotides (cyclic AMP and cyclic GMP) were measured in gerbil cortex during ischemia and recirculation. Bilateral ischemia of the gerbil brain was chosen as a model to ensure the assessment of short periods of ischemia without ambiguity. The metabolites and cyclic nucleotides were measured after, 1, 5. 20. 30 and 60 min of ischemia; and 1, 5, 30, 60 and 360 min after circulation was reestablished. The greatest changes in metabolites and cyclic nucleotides due to ischemia occurred during the 1st min; ischemia of longer duration had little further effect. However, the restoration of the metabolic profile was altered by the duration of the ischemic period. In general, the longer the period of ischemia, the slower the replenishment of high‐energy phosphate compounds and energy sources. Cyclic AMP increased 5‐ to 13‐fold during ischemia; cyclic GMP decreased to as little as one‐fifth control values 60min after occlusion. During recirculation, cyclic AMP increased as much as 100‐fold, while cyclic GMP increased up to 6‐fold. The temporal derangements in cyclic nucleotide concentrations coincide with the loss and restoration of cortical activity; a possible mechanism has been suggested.
REDISTRIBUTION OF ADENINE DERIVATIVES AMONG SUBCELLULAR FRACTIONS FROM GUINEA PIG NEOCORTICAL TISSUES, ON INCUBATION IN VITRO
Authors: Barberis C. , McIlwain H.
Published: October 2006

Abstract— After the brief in vitro exposure of guinea‐pig neocortical tissue to [14C]adenine, synaptosomal fractions prepared from the incubated tissue contained about 6% of its retained 14C. On continued incubation and superfusion with or without stimulation, the synaptosomal proportion of the 14C increased, while the protein and K content of the fraction underwent smaller changes only. Colchicine, 0.5 mm, diminished the synaptosomal enrichment in [14C]adenine derivatives and also in some cases increased the 14C effluent from tissues to superfusates. Colchicine also diminished the uptake of adenosine, but not of adenine, to the neocortical tissues. It is concluded that nerve terminal regions receive adenine derivatives from other tissue components as part of their normal metabolism, and that much of this can arrive by extracellular fluids; transport cytoplasmically is not excluded.
14C‐LABELLED AMINO ACIDS AND GLUCOSE IN RAT BRAIN AND LIVER AFTER INJECTION OF [2‐14C]PROPIONATE
Authors: Gaitonde M. K. , Wharton J. , Holt Elizabeth
Published: October 2006

Abstract— [2‐14C]Propionate injected into rats was metabolized into [14C]glucose and 14C‐labelled aspartate, glutamate, glutamine and alanine. The results are consistent with the conversion of propionate into succinate and the oxidation of succinate into oxaloacetate, the precursor of labelled amino acids and the substrate for gluconeogenesis.

The ratio of the specific radioactivity of glutamine to glutamate was greater than 1 during the 30 min period in the brain, indicating that propionate taken up by the brain was metabolized mainly in the ‘small glutamate compartment’ in the brain. The results, therefore, support the previous conclusion (Gaitonde, 1975) that the labelling of amino acids by [14C]propionate formed from [U‐14C>]‐threonine in thiamin‐deficient rats was metabolized in the ‘large glutamate compartment’ of the brain.

The specific radioactivity ratio of glutamine to glutamate in the liver was less than 1 during the 10 min period but greater than 1 at 30min. These findings which gave evidence against metabolic compartments of glutamate in the liver, were interpreted as indicative of the entry of blood‐borne [14C]glutamine synthesized in other tissues, e.g. brain. The labelling of amino acids when compared to that after injection of [U‐14C]glucose showed that [2‐14C]propionate was quantitatively a better source of amino acids in the liver. The concentration of some amino acids in the brain and liver was less in the adult than in the young rats, except for alanine and glutathione, where the liver content was more than double that in the adult.
THE EFFECT OF Cl− ON CHOLINE ACETYLTRANSFERASE KINETIC PARAMETERS AND A PROPOSED ROLE FOR Cl− IN THE REGULATION OF ACETYLCHOLINE SYNTHESIS
Authors: Rossier Jean , Spantidakis Youlie , Benda Philippe
Published: October 2006

Abstract— Crude or purified rat brain choline acetyltransferase (ChAc) is activated by anions. Among anions, Cl− is the most effective and may promote an up to 60 fold increase in Vmax. In the absence of Cl−, at low ionic strength, acetylcholine (ACh) is a good ChAc inhibitor (Ki= 0.310 mm). The ACh inhibition becomes negligible when Cl− is increased to 145 mm (ACh Ki= 45 mm). These results are discussed in terms of regulation of ACh synthesis by nerve terminals. It is proposed that ChAc is part of a presynaptic membrane bound multienzymatic complex under direct control of the ion fluxes promoted by nerve impulses.
ALTERED THYMIDINE KINASE OR THYMIDYLATE SYNTHETASE ACTIVITIES IN 5‐FLUORO DEOXYURIDINE RESISTANT VARIANTS OF MOUSE NEUROBLASTOMA1
Authors: Baskin F. , Davis R. , Rosenberg R. N.
Published: October 2006

Abstract: Abstract‐We have previously described a 5‐fluorodeox yuridine (FUdR) resistant neuroblastoma variant, possessing normal levels of ATP: thymidine‐5‐phosphotransferase (EC 2.7.1.21) [trivial name: thymidine kinase (TK)] but an 8‐fold elevation in methy1enetetrahydrofolate:dUrd‐5′P C‐methyltransferase (EC 2.l.l.b) [trivial name: thymidylate synthetase (TS)] relative to the drug‐sensitive parental clone. This variant possesses elevated levels of the parental TS species, 30% of which is uninhibitable by in vivo pulses of FUdR, suggesting the subcellular compartmentalization of this enzyme. We contrast this variant with a second FUdR resistant clone isolated from an ethyl‐methane‐sulfonate mutagenized population of the parental clone. This variant displays a 96% reduction in TK specific activity, despite normal FUdR and thymidine uptake rates, demonstrating the independence of thymidine phosphorylation and uptake. Grown without drug, its resistance declines (half‐life of 15 cell divisions) with its TK specific activity rising to a plateau of 16% of the parental level after 56 cell divisions. Thymidine (1.0μM) protects the TK+ but not the TK‐ variants from FUdR induced growth inhibition but is without effect on TS specific activity. Unlike Tetrahymena (DICKENS et al., 1975), neuroblastoma TS activities appear not to be regulated by adenosine or guanosine cyclic nucleotide levels.
NUCLEAR CHROMATIN PROTEINS FROM RABBIT CEREBRUM, CEREBELLUM AND LIVER: SYNTHESIS AND PHOSPHORYLATION
Authors: Oh'Hara Ikuko , Yanagihara Takehiko
Published: October 2006

Abstract— In order to investigate synthesis and phosphorylation of the various fractions of nuclear proteins. [3H]leucine and [32P] phosphate incorporation were studied with tissue slices in vitro. Cerebral cortex and cerebellum were used to delineate the similarity and dissimilarity within CNS, and liver was taken to compare the extraneural organ. There were significant differences in [3H]leucine incorporation into nuclear proteins among those tissue sources examined, while [32P]phosphate incorporation showed very similar results among them. Although the acidic chromatin protein demonstrated high activity in each tissue source for both synthesis and phosphorylation, 0.14M‐NaCl soluble protein showed the activity as high as or even higher than the acidic chromatin protein. Both [3H]leucine incorporation and [32P]phosphate incorporation were relatively low in histone. When the acidic chromatin protein was further fractionated with SDS‐acrylamide gel electrophoresis, significant difference was found between CNS tissue and liver for synthesis and phosphorylation. However, considerable difference was also observed even between cerebral cortex and cerebellum. The present investigation demonstrated complicity and diversity of nuclear chromatin proteins in different organs, not only for their protein constituents but also for their synthesis and phosphorylation.
THE MAJOR SITE OF GUINEA‐PIG MYELIN BASIC PROTEIN ENCEPHALITOGENIC IN LEWIS RATS12
Authors: Chou C.‐H. J. , Chou F. C.‐H. , Kowalski T. J. , Shapira R. , Kibler R. F.
Published: October 2006

Abstract—

In the Lewis rat, fragment 43–88 of the highly encephalitogenic guinea‐pig basic protein has been previously shown to retain the full activity of the parent protein. In the present studies this fragment was subjected to controlled chymotryptic digestion so that cleavage occurred only at tyrosine 67, generating two peptides, residues 43‐67 and residues 68‐88. When compared on an equimolar basis peptide 68‐88 had the same encephalitogenic activity as the intact fragment and induced the same degree of immunologically specific cell response as measured by the in vitro lymphocyte stimulation test. Peptide 68‐88 was further fragmented by selective tryptic cleavage at arginine 78 after blocking lysine 73 with citraconic anhydride. The two peptides, residues 68‐78 and residues 79‐88, were not encephalitogenic, indicating that residues adjacent to the point of cleavage contribute to the active site.
BRAIN CONCENTRATIONS OF BIOGENIC AMINES AND THEIR METABOLITES IN TWO TYPES OF PYROGEN‐INDUCED FEVER IN RABBITS
Authors: Gardey‐Levassort Christiane , Tanguy Odette , Lechat P.
Published: October 2006

Abstract—

The effects of two bacterial pyrogens (gonococcus vaccine and E. coli lipopolysaccharide) on brain and CSF concentrations of the biogenic amines and their major metabolites were compared in rabbits. Both pyrogens induced a similar fever, but only the lipopolysaccharide elicited marked biochemical alterations. The main changes observed were: a decrease in the concentrations of acid metabolites of dopamine during the upward course of the first peak of fever; a decrease in the hypothalamic concentrations of noradrenaline at the second peak of fever; a general increase in the metabolites of biogenic amines around the second peak and during the fall of fever. The results led to the conclusion that no significant correlation exists between body temperature and brain amine levels in rabbits. The alterations observed could be a consequence of the fever itself when considered in terms of trauma to the organism.
STUDIES ON THE MECHANISM OF DEMYELINATION: MYELIN AUTOLYSIS IN NORMAL AND EDEMATOUS CNS TISSUE
Authors: SMITH MARION EDMONDS
Published: October 2006

Abstract—

The effects on myelin of autolysis in situ after death and after purification were studied in normal brains and spinal cords and in those made edematous as a result of chronic triethyl tin (TET) feeding. Myelin prepared from normal and edematous brains and spinal cords autolyzed for 12 h at 4°C contained only slightly less basic protein than that prepared from freshly killed animals. The amounts of a light lipid‐protein fraction (dissociated myelin) usually obtained during purification of myelin from edematous CNS were about the same in tissue from freshly killed rats and those autolyzed for 12 h at 4°C. Autolysis for 12 h at room temperature resulted in formation of large amounts of dissociated myelin and loss of basic protein, but more dissociation and basic protein loss occurred in CNS from edematous brains and spinal cords than from the normal. Purified myelin prepared from freshly‐killed normal and TET‐fed rats was incubated at 37°C in media of several ionic strengths. In Krebs‐Ringer bicarbonate (physiological extracellular fluid) extensive dissociation of myelin occurred with much less in 0.04 M‐Tris buffer, pH 7.2, and only small amounts were formed in 0.01 M‐Tris. In all cases myelin from edematous CNS formed more dissociated fraction than did the normal myelin. Basic protein loss was also proportional to the ionic strength of the media, but there was no difference in loss between normal and TET‐myelin. Two different factors, proteolysis and physical extraction of basic protein by salt solutions, may be contributing to myelin dissociation and loss of basic protein.
NONRIBOSOMAL INCORPORATION OF AMINO ACIDS INTO THE TROPONIN‐LIKE PROTEIN FROM SYNAPTOSOMES
Authors: CARLIN R. K.
Published: October 2006

Abstract—

A preparation of synaptosomal cytoplasm was isolated from forebrain of young rats and incubated with various amino acids in vitro. Incorporation of amino acids into protein was observed. This incorporation did not occur by ribosomal protein synthesis. The amino acid incorporating system was not stimulated by ATP and was inhibited by calcium. The system incorporated amino acids enzymatically.

An electrophoretic analysis of the synaptosomal preparation, following incubation in the presence of radioactive amino acids, showed only three labelled protein species (molecular weights 37,000, 26,000 and 20,000). This incorporation of amino acids was found to have a high degree of specificity for three protein species. Migration of the three protein species was found to be nearly identical to that of rabbit muscle troponin. The proteins incorporating amino acids were also found to have other characteristics of the troponin subunits. A possible role of troponin modification is discussed.