bluuebunny/crossref_metadata_2025_split huggingface dataset:
FETAL DEVELOPMENT: THE EFFECTS OF MATURATION ON IN VITRO PROTEIN SYNTHESIS BY MOUSE BRAIN TISSUE
Authors: Gilbert B. E. , Johnson T. C. 
Published: October 2006

Abstract—The elucidation of the translational regulatory events which function during the critical fetal and neonatal period is an important prerequisite to our understanding of normal, as well as abnormal, brain growth and differentiation. Brain cell suspensions and cell‐free homogenates were employed to study the protein synthetic activity during the maturation of fetal‐ neural tissue. The results clearly demonstrated that while neural tissue from 1‐day postnatal mice was 10 times more active in protein synthesis than brain tissue from adult mice, the former was many fold less active in translational events than fetal neural tissue from 13‐day post‐zygotic mice. Fetal polypeptide synthetic activity was found to decrease from the 13th day to the 19th day post‐zygotic. This decrement in the translational activity was not due to amino acid availability or pools, or to differences, quantitatively or qualitatively, in polysome concentrations. The enhanced rate of protein synthetic activity measured with neural tissue from 13‐day post‐zygotic mice was shown to be due to an increase in rate of protein synthesis and not to an enhanced rate of protein degradation.
IN VITRO Ca2+ DEPENDENT PROTEOLYSIS IN BRAIN TISSUES: A POSSIBLE SOURCE OF ERROR IN TRANSMITTER METABOLISM STUDIES
Authors: Hamon M. , Bourgoin S. , Hery F. , Glowinski J. 
Published: October 2006

Abstract—The effects of Ca2+ ions on the metabolism of [3H]serotonin and [3H]‐labelled catecholamines have been examined in hippocampal slices or synaptosomes. The formation of [3H]‐5 hydroxyindoles ([3H]serotonin + [3H]‐5 hydroxyindoleacetic acid) from [3H]tryptophan and that of [3H]‐labelled catecholamines from [3H]tyrosine were increased when Ca2+ was omitted from the incubating medium. However, the total synthesis of 5‐HT from tryptophan and that of catecholamines from tyrosine did not seem to be significantly changed. Altered formation of tritiated amines were due to changes in the specific activities of respective precursor amino acids. This reflected altered sizes of the free amino acid pools caused by Ca2+‐dependent in vitro proteolysis. This must be taken into consideration when studying in vitro Ca2+ dependency of neutrotransmitter metabolism.
DEPLETION OF TRYPTOPHAN HYDROXYLASE BY 5,6‐DIHYDROXYTRYPTAMINE IN RAT BRAIN—TIME COURSE AND REGIONAL DIFFERENCES1
Authors: Victor S. J. , Baumgarten H. G. , Lovenberg W. 
Published: October 2006

Abstract—Wistar rats were injected intraventricularly with 75 μg 5,6‐dihydroxytryptamine. Tryptophan hydroxylase was assayed in seven regions of the brain as well as spinal cord at intervals following injection. Spinal cord was depleted to 1 per cent of control by 12 days. Tectum was depleted to 32 per cent of control by 9 days. The time course of depletion in most regions was biphasic, with an early reduction of activity 1 h after injection with continued reduction of activity 1‐2 days following injection, and a recovery of activity at 4‐6 days. The activity again drops at 9‐12 days, and this reduction of activity persists to varying degrees to 60 days, with slight recovery at this time in certain regions.
CHANGES WITHIN METABOLIC COMPARTMENTS IN THE BRAINS OF YOUNG RATS INGESTING LEAD
Authors: Patel A. J. , Michaelson I. A. , Cremer J. E. , Balázs R. 
Published: October 2006

Abstract—[2‐14C]Glucose and [3H]acetate were injected simultaneously into 19‐day‐old rats suckling from mothers fed either a normal diet or a diet containing 4·5% lead acetate. Changes in the rate of conversion of both precursors into amino acids associated with the tricarboxylic acid cycle were observed.[I4C]Glucose. In the brain of young rats ingesting lead, the specific radioactivity of glutamate, aspartate, γ‐aminobutyrate and glutamine were all significantly lowered relative to that of glucose. Glutamine labelling was the most affected.[3H]Acetate. In comparison with controls, the total amount of 3H in either water or acid‐soluble constituents of the brain was the same, but the 3H content of the amino acids was significantly reduced in the lead‐treated rats. In both groups, glutamine had the highest specific radioactivity but the time courses of the labelling of glutamine were different. In the control the peak incorporation was reached during the first 5 min, whereas in the experimental animals this occurred at about 10 min after the injection of the precursor, and the specific radioactivity even at that time was less than in controls. When compared with controls, the depression in the labelling of glutamine was accompanied at 5 min by an increase in the specific radioactivity of aspartate. In the lead‐treated rats the labelling of GABA was also slowed and the time course seemed to follow that of glutamine rather than glutamate. In spite of the differences in the metabolism of [3H]acetate, metabolic compartmentation of glutamate, assessed by a glutamine : glutamate specific radioactivity ratio higher than 1, was evident even in the brain of the lead‐treated animals, although the values of the ratio at 5 and 10 min were less than in controls. There was no evidence of a diminished supply of substrates to the brain in lead intoxication. The overall changes would be consistent with a retardation in the biochemical maturation of the brain in terms of development of glucose metabolism and metabolic compartmentation.
CHOLINERGIC STIMULATION OF PHOSPHOLIPID LABELLING FROM [32P]ORTHOPHOSPHATE IN GUINEA‐PIG CORTEX SYNAPTOSOMES IN VITRO: SUBSYNAPTOSOMAL LOCALIZATION
Authors: Schacht J. , Neale Elaine A. , Agranoff B. W. 
Published: October 2006

Abstract— Subsynaptosomal localization of stimulation of phospholipid labelling by cholinergic agents was investigated. Synaptosomes prepared from guinea‐pig cortex were incubated with [32P]orthophosphate in the presence or absence of 10−3m carbamylcholine. Following incubation and osmotic shock, lysed synaptosomes were subjected to density gradient fractionation. Subsynaptosomal fractions were examined by electron microscopy and analysed for enzyme activities and 32P‐labelled lipids.In the absence of carbamylcholine, labelled phosphatidate and phosphatidylinositol were recovered in layers and interfaces A, B, C and D formed over 0.9, 1.1, 1.2 and 1.3 m sucrose, with highest amounts of label in fractions C and D for both lipids. Carbamylcholine induced the greatest increment in these two labelled lipids in fractions A and B. This distribution correlated with the presence of acetylcholinesterase activity and membrane ghosts. No correlation was found among the four fractions between the induced increase in labelling and succinic dehydrogenase activity or with the abundance of mitochondria, synaptic vesicles, or cytoplasmic fragments identified by electron microscopy. In contrast with the increases seen in phosphatidylinositol and phosphatidate labelling, carbamylcholine caused a decrease in 32P‐labelling of the polyphosphoinositides, and this effect was seen primarily in the heavier subsynaptosomal fractions, C and D.
METABOLIC COMPARTMENTATION IN THE BRAIN: EFFECTS OF A CENTRAL NERVOUS SYSTEM DEPRESSANT, 1‐HYDROXY‐3‐AMINO‐PYRROLIDONE‐2
Authors: Mouhler H. , Patel A. J. , Johnson A. L. , Reynolds A. P. , Balazs R. 
Published: October 2006

Abstract—The effect of 1‐hydroxy‐3‐aminopyrrolidone‐2(HA‐966), a CNS depressant, was studied on the metabolism of [14C]glucose and [3H]acetate in the brain in mice. HA‐966 had a marked effect on glucose metabolism. The conversion of glucose carbon into amino acids associated with the tricarboxylic acid cycle (‘cycle’) was severely reduced, while the concentration of brain glucose was approximately doubled. Relative to the specific radioactivity of glucose in the brain, the specific radioactivity of alanine was 60–70 per cent of the control, indicating a reduction in the rate of glycolysis, and those of the‘cycle’amino acids were also lowered. A reduction in‘cycle’flux of 30–35 per cent was estimated. It was established that the depressed glucose utilization flux was not due to either impaired uptake of glucose from blood to brain or to hypothermia. In contrast to [14C]glucose, there was no change in the labelling of the amino acid fraction from [3H]acetate, which is preferentially metabolized in the 'small’compartment believed to be associated with glia. Thus it seems that CNS depression caused by HA‐966 resulted in a selective decrease in energy production in the‘large’metabolic compartment where glucose is oxidized preferentially and which is believed to be associated with neuronal structures.The results also suggested that communication between the metabolic compartments mediated via glutamine and GABA was reduced, since the labelling from [3H]acetate of glutamine was increased and that of GABA decreased by HA‐966.
METHYLATED AMINO ACID RESIDUES OF PROTEINS OF BRAIN AND OTHER ORGANS
Authors: Kakimoto Y. , Matsuoka Y. , Miyake M. , Konishi H. 
Published: October 2006

Abstract—Methods for the determination of methyl‐lysine, methyllarginine and methylhistidine residues of tissue proteins are described. They consist of preliminary purification of basic amino acids, enzymic removal of lysine, arginine and histidine followed by amino acid analysis. Recovery rates and specificities of the method were satisfactory. The contents of methylamino acids in proteins of mammalian organs were determined.The distribution of proteins containing the methylamino acids in human brain showed that the concentrations of methyl‐lysine and NG,N′G‐dimethylarginine were highest in the gray matter of the cerebellar cortex and relatively high in regions rich in gray matter, while those of NG‐mono‐ and NG,N′G‐dimethylarginine were highest in the white matter. The following findings suggest that most of the NG‐mono‐ and NG,N′G‐dimethylarginine was associated with the myelin basic protein. The distribution of the methylarginine residues of acid‐soluble proteins in bovine brains coincided with the cerebroside pattern. The concentrations of the amino acids in acid‐soluble proteins of rat brain increased concomitantly with the increase of cerebroside. The methylamino acid content in proteins increased during the purification of the myelin basic protein from the white matter of human and bovine brains.Proteins containing NG,NG‐dimethyiarginine and di‐ and trimethyl‐lysine are concentrated in cell nuclei. The first amino acid was found mainly in nucleoplasmic proteins and the other two were found in histones. The concentration of 3‐methylhistidine residue, highest in muscular proteins, is low in cerebral proteins and is probably derived from proteins of walls of blood vessels in the brain.
ELEVATION OF BRAIN HISTAMINE CONTENT IN PROTEIN‐DEFICIENT RATS1
Authors: Enwonwu Cyril O. , Worthington Bonnie S. 
Published: October 2006

Abstract—Male rats of the Sprague‐Dawley strain (80–250 g body wt) were fed either an adequate protein diet (18% lactalbumin) or a protein‐deficient diet (0.5% lactalbumin). After 5–8 weeks of receiving the low protein diet, some of the malnourished rats were rehabilitated with an adequate protein diet. The malnourished rats exhibited significant elevations in brain levels of histidine (+415%) and homocarnosine (+100%) in comparison to findings in the control animals of similar age. Associated with the elevated brain levels of histidine in malnutrition was a prominent increase in brain content of histamine (+ 150‐+ 238%). The mean brain histamine levels (ng/g) in the control rats varied from 45.96 to 56.15 in several experiments. In the protein‐deficient rats, values ranged from 115 to 190. Refeeding the malnourished rats with adequate protein diet elicited reversal of histidine and histamine levels to near normal values within 1 week. The increased brain content of histamine in malnutrition was attributed to enhanced rate of production resulting from increased availability of the precursor amino acid, a conclusion consistent with elevation also of the brain content of homocarnosine (γ‐aminobutyryl‐l‐histidine) which is another major route of disposal of histidine in the brain. The relevance of these neurochemical alterations to the behavioural changes often associated with protein malnutrition, deserves some intensive examination.
THE PRESENCE OF CYSTEINE IN FROG MYELIN BASIC PROTEIN
Authors: Martenson R. E. , Deibler Gladys E. , Kramer A. J. 
Published: October 2006

Abstract—Frog myelin basic protein, when subjected to ion‐exchange chromatography at alkaline pH, underwent conversion to a higher molecular weight form. Treatment of the latter with 2‐mercaptoethanol regenerated the monomeric basic protein. Amino acid analysis of the monomer and the higher molecular weight species after performic acid oxidation demonstrated the presence of approximately 1 mol of cysteic acid per mol of protein of molecular weight 19,700. Treatment of the monomer with the mild oxidizing agent azodicarboxylic acid bis dimethyl amide resulted in its partial conversion to the higher molecular weight form. These studies demonstrate that the frog myelin basic protein, unlike those of all other species hitherto examined, contains a single cysteinyl residue in its polypeptide chain.
THE PROPORTIONATE LOSS OF l‐3,4‐DIHYDROXYPHENYLALANINE AND l‐5‐HYDROXYTRYPTOPHAN DECARBOXYLATING ACTIVITY IN RAT CENTRAL NERVOUS SYSTEM FOLLOWING INTRACISTERNAL ADMINISTRATION OF 5,6‐DIHYDROXYTRYPTAMINE OR 6‐HYDROXYDOPAMINE
Authors: Dairman W. , Horst W. Dale , Marchelle Mary E. , Bautz G. 
Published: October 2006

Abstract—5,6‐Dihydroxytryptamine or 6‐hydroxydopamine was administered intracisternally to rats to effect a selective destruction of serotonin or catecholamine‐containing neurons. The l‐DOPA and l‐5‐hydroxytryptophan decarboxylating activities of the spinal cord and brain were then determined at several time intervals following this treatment. In both cases the relative loss of l‐DOPA decarboxylating activity was the same as the relative loss of l‐5‐hydroxytryptophan decarboxylating activity. 5,6‐Dihydroxytryptamine treatment had little or no effect on catecholamine‐containing neurons and 6‐hydroxydopamine did not effect serotonin‐containing neurons. These data support the idea that only one decarboxylase is involved in the biosynthesis of both serotonin and catecholamines in the rat CNS.
A SENSITIVE MICROASSAY FOR TRYPTOPHAN HYDROXYLASE IN BRAIN
Authors: Kizer J. S. , Zivin J. A. , Saavedra J. M. , Brownstein M. J. 
Published: October 2006

Abstract—A specific and sensitive, radioisotopic microassay for tryptophan hydroxylase (EC 1.14.36) is described, which is capable of determining enzymatic activity in as little as 5 μg of crude brainstem homogenate. 5‐Hydroxytryptophan, the immediate product of hydroxylation of tryptophan is enzymatically converted to N‐acetylserotonin. A radioisotopic label is then introduced by the enzymatic methylation of N‐acetylserotonin in the presence of [3H]methyl‐S‐adenosyl‐methionine. The [3H]‐melatonin thus formed is isolated by extraction and counted.With this assay, the activity in individual hypothalamic nuclei (arcuate nucleus, median eminence, suprachiasmatic nucleus, and medial forebrain bundle) has been measured.
PROTEIN PATTERNS IN DIFFERENT LOBES AND DURING DEVELOPMENT OF OCTOPUS BRAIN
Authors: Giuditta A. , Cimarra Patrizia , Prozzo Nicola 
Published: October 2006

Abstract— Utilizing techniques of continuous and SDS‐electrophoresis we have examined the saline‐soluble and SDS‐soluble (membrane‐bound) proteins extracted from the main lobes of adult octopus brain and from the developing optic lobe of the same species. Several additional protein bands are present among the soluble and the membrane‐bound proteins of the vertical lobe in comparison with the suboesophageal lobe. Since the former contains an essentially homogeneous population of small neurons, while the suboesophageal lobe is rich in large nerve cells, these protein bands have been attributed to the small neuronal type present in the vertical lobe.In the course of a 10,000‐fold increment in body weight, from 0.4 g to 4 kg, there is a significant increase in the concentration of several soluble proteins extracted from the optic lobe. Three of these proteins increase to a marked degree. Among the membrane‐bound proteins some show a moderate increase with age while other protein components of smaller molecular weight undergo a moderate decrease. The overall tissue concentration of the membrane‐bound proteins increases between 0.4 g and 50 g body weight, slightly declining in animals of larger size.
THE SUBCELLULAR LOCALIZATION OF Ach SYNTHESIS IN RAT STRIATAL SYNAPTOSOMES INVESTIGATED WITH THE USE OF TRITON X‐100
Authors: Lefresne P. , Guyenet P. , Beaujouan J. C. , Glowinski J. 
Published: October 2006

Abstract—The regulation of [14C]ACh synthesis was studied in rat striatal synaptosomes incubated in presence of various concentrations of Triton X‐100, using [2‐14C]pyruvate or [6‐14C]glucose as precursors. The progressive rupture of the cytoplasmic and mitochondrial compartments induced by the non‐ionic detergent was followed by studying the release, into the incubating medium, of lactate dehydrogenase and choline acetyltransferase (ChAc) and of fumarate hydratase, respectively. [3H]Choline uptake (1 μm) was measured to determine the activity of the high affinity choline permease. 14CO2 formation from [2‐14C]pyruvate was used as an index of the Krebs cycle activity.The rate of [14C]ACh synthesis from [2‐14C] pyruvate was dependent on the Triton X‐100 concentration; the ester formation decreased between 0·001% (v/v) and 0·010%, but increased again beyond this concentration of detergent. This last phenomenon was interpreted as the result of an extracellular synthesis of ACh involving pyruvate dehydrogenase and ChAc. At 0·002% Triton X‐100 the 14CO2 formation was not affected, indicating a normal mitochondrial activity. The decrease of [14C]ACh synthesis observed up to this detergent concentration could be correlated to the decline of the highaffinity choline permease activity. In these experimental conditions, the ester synthesis could not be restored by the addition of large amounts of choline in the incubating medium suggesting that the molecules of choline must cross the high‐affinity choline permease system in order to be acetylated. This could indicate a close association between the permease and choline acetyltransferase.
EFFECT OF GTP AND OTHER NUCLEOSIDE TRIPHOSPHATES ON GMP INCORPORATION BY ISOLATED CORTICAL NUCLEI
Authors: Ferchmin P. A. , Morimoto H. , Bennett E. L. 
Published: October 2006

Abstract—The concentration of GTP was found to be critically important in determining the characteristics of incorporation of GMP by DNA‐dependent RNA polymerase from rat brain nuclei. The linearity of the incorporation rate was related to the log of the GTP concentration. Three hundred μM‐GTP in the presence of the other nucleoside triphosphates (1 mM) was near to the optimal conditions in terms of maximum incorporation and linearity. The concentration of ammonium sulfate was an important factor in determining the maximum GMP and UMP incorporation. The U/G incorporation ratio was less than one at low concentrations of substrate and increased with increasing substrate or ammonium sulfate concentration. α‐Amanitin strongly inhibited the reaction, indicating that RNA polymerase II is the effective enzyme.
THE MECHANISM OF ACTION OF β‐BUNGAROTOXIN
Authors: Wernicke J. F. , Vanker A. D. , Howard B. D. 
Published: October 2006

Abstract—β‐Bungarotoxin, a presynaptically‐acting polypeptide neurotoxin, caused an efflux from synaptosomes of previously accumulated γ‐aminobutyric acid and 2‐deoxy‐d‐glucose. The toxin‐induced efflux of γ‐aminobutyric acid occurred by a Na+ ‐dependent process while that of 2‐deoxyglucose was Na+ ‐independent. These effects were also produced by treating synaptosomes with low molecular weight compounds, including fatty acids, that inhibit oxidative phosphorylation. After incubation with β‐bungarotoxin, synaptosomes exhibited increased production of 14CO2 from [U‐14C]glucose and decreased ATP levels. β‐Bungarotoxin treatment of various subcellular membrane fractions caused the production of a factor that uncoupled oxidative phosphorylation when added to mitochondria. Mitochondria from toxin‐treated brain tissue exhibited a limitation in the maximal rate of substrate utilization. We conclude that β‐bungarotoxin acts by inhibiting oxidative phosphorylation in the mitochondria of nerve terminals. This inhibition accounts for the observed β‐bungarotoxin effects on synaptosomes and at neuromuscular junctions. We suggest that the effects on energy metabolism result from a phospholipase A activity found to be associated with the toxin.
THE EFFECT OF A LOW PROTEIN DIET AND EXOGENOUS INSULIN ON BRAIN TRYPTOPHAN AND ITS METABOLITES IN THE WEANLING RAT
Authors: Dickerson J. W. T. , Pao S.‐K. 
Published: October 2006

Abstract—Male Wistar rats aged 24 days were divided into three groups. Two groups were given a high protein (250 g/kg casein) and a low protein (30 g/kg casein) diet respectively. The third group was given an amount of the high protein diet containing the same amount of energy as that consumed by the low protein diet rats. The plasma of the animals on low protein contained 20% of the concentration of tryptophan of animals on the other two diets. In these animals the concentration of tryptophan was reduced in the forebrain, cerebellum and brain stem, and the concentrations of 5‐HT and 5‐hydroxyindoleacetic acid were reduced in the forebrain and brain stem. The low protein diet decreased the total uptake of l‐[G‐3H]tryptophan into the brain and its incorporation into brain protein. Plasma insulin concentrations were reduced in the low protein and ‘restricted high protein’ animals and the plasma corticosterone concentration was raised in the low protein animals. Exogenous insulin did not raise the plasma tryptophan concentration in the low protein animals but it increased the uptake of l‐[G‐3H]tryptophan into the brain and its incorporation into protein. Rehabilitation for 7 days restored the plasma and brain tryptophan concentrations and those of brain 5‐HT and 5‐hydroxyindoleacetic acid to control values.
FRACTIONATION OF SPECIFIC MITOCHONDRIAL AND CYTOPLASMIC tRNAs OBTAINED FROM CALF BRAIN1
Authors: Borkowski T. , Brzuszkiewicz‐Żarnowska H. 
Published: October 2006

Abstract—Total tRNA fractions were isolated from pure mitochondrial and cytoplasmic calf brain preparations. After incubation with homologous crude preparations of aminoacyl‐tRNA ligases in the presence of [14C]‐glutamic acid, tRNAs were separated chromatographically on BD‐cellulose columns and in reversed phase chromatography systems. In both of the methods used, cytoplasmic tRNA preparations revealed a larger number of radioactivity peaks. In experiments with double labelling, five radioactivity peaks for cytoplasmic glutamyl‐tRNAs corresponded to only three mitochondrial glutamyl‐tRNA fractions. The results imply the presence of isoaccepting species of tRNA in brain.