bluuebunny/crossref_metadata_2025_split huggingface dataset:
MULTIPLE FORMS OF MONOAMINE OXIDASE IN DEVELOPING BRAIN: TISSUE AND SUBSTRATE SPECIFICITIES
Authors: Shih Jean‐Hung C. , Eiduson S. 
Published: October 2006

AbstractBrains, hearts and livers from newborn and adult rats were assayed for monoamine oxidase activity using gel electrophoretic techniques. The results suggest that each of the tissues possesses multiple forms (isoenzymes) of monoamine oxidase and that these forms are different for the various tissues. Further, the forms of monoamine oxidase in the neonatal tissues differ from those in the corresponding adult tissue. These different forms of monoamine oxidase have different substrate specificities. Using 5‐hydroxy[14C]tryptamine as substrate, we have demonstrated that the monoamine oxidase patterns appearing on the gel do indeed possess monoamine oxidase activity.
PHOSPHOFRUCTOKINASE AND FUMARATE HYDRATASE IN DEVELOPING RAT BRAIN
Authors: Adlard B. P. F. , Dobbing John 
Published: October 2006

AbstractThe developmental patterns of phosphofructokinase, fumarate hydratase and lactate dehydrogenase were determined and compared using homogenates of rat brain. Phosphofructokinase activity, expressed in terms of tissue wet wt., was relatively constant from 5 days before birth to 8 days postnatal; a 110 per cent increase in activity occurred between 12 and 21 days of age, when adult levels were achieved. The degree of inhibition of phosphofructokinase by 1‐0 mM‐ATP changed little during development; inhibition by 2‐5 mM‐citrate was about 50 per cent in both newborn and adult brain. Phosphofructokinase development more closely resembled that of lactate dehydrogenase than that of fumarate hydratase.
EFFECTS OF A NERVE‐GROWTH FACTOR, EMBRYO AGE AND METABOLIC INHIBITORS ON GROWTH OF FIBRES AND ON SYNTHESIS OF RIBONUCLEIC ACID AND PROTEIN IN EMBRYONIC SYMPATHETIC GANGLIA1
Authors: Partlow L. M. , Larrabee M. G. 
Published: October 2006

AbstractIncorporation of labelled precursors into RNA and protein was measured in lumbar sympathetic ganglia from chicken embryos (usually 13‐14 days old) in the presence . or absence of nerve‐growth factor. The ganglia were incubated with labelled precursors while embedded in plasma clots, so that the outgrowth of nerve fibres could be measured in the same ganglia as the incorporation. Fibre outgrowth was estimated quantitatively by the use of a newly‐devised objective measure of mean halo width.In controls without the nerve‐growth factor, there was an abrupt slowing of labelling of both RNA and protein after 6‐12 h. This slowing was greatly delayed or prevented by addition of the growth factor. At earlier times, small increases in incorporation of both labels accompanied addition of the growth factor, but were not always statistically significant.When ganglia were incubated for 28 h with labelled precursors in the presence of the growth factor, 11 per cent of both the labelled protein and the labelled RNA were found in the halos of outgrowing fibres and 89 per cent in the bodies of the ganglia. In ganglia from embryos of different ages, there was a maximum of labelling per unit volume of ganglion in both RNA and protein at 10 days and a minimum at 12 days of embryonic age. The growth factor increased the labelling during 22 h of incubation at most ages, regardless of whether outgrowth of fibres was great (13‐14 days) or minimal (9‐10 days).Almost total inhibition of RNA labelling by actinomycin‐D caused only moderate impairment of fibre outgrowth. Actinomycin‐D also somewhat reduced protein labelling. Cyclo‐heximide, in concentrations which produced degrees of inhibition of protein labelling identical to those of actinomycin‐D, caused similar impairment of fibre outgrowth. We conclude that RNA synthesis is not essential to the initiation of fibre outgrowth by the nerve‐growth factor.
THE EFFECTS OF PSYCHOACTIVE AGENTS ON CALCIUM UPTAKE BY PREPARATIONS OF RAT BRAIN MITOCHONDRIA12
Authors: Tjioe Sarah , Haugaard N. , Bianchi C. P. 
Published: October 2006

AbstractThe effects of chlorpromazine and other psychoactive agents on the uptake of calcium by partially purified preparations of mitochondria from rat brain were studied in vitro. Chlorpromazine at concentrations of about 0‐1 ITIM caused a marked inhibition of mitochondrial calcium transport. Perphenazine also exhibited this action and was slightly more potent than chlorpromazine. Imipramine inhibited mitochondrial calcium uptake but higher concentrations were necessary than in experiments with chlorpromazine. The sulph‐oxide of chlorpromazine did not inhibit calcium transport when tested at concentrations similar to those used with chlorpromazine. Up to concentrations of 20 mM, lithium ions did not influence mitochondrial calcium uptake.
THE ACTION OF GAMMA‐HYDROXYBUTYRIC ACID ON CEREBRAL GLUCOSE METABOLISM
Authors: Taberner P. V. , Rick J. T. , Kerkut G. A. 
Published: October 2006

Abstract— Experiments have been performed to study the effect of gamma‐hydroxybutyric acid (GHB) on glucose metabolism in vivo and in vitro.

Administration of GHB (500 mg/kg) is followed by sleep in rats and mice.
GHB is shown to increase the 1‐14C/6‐14C ratio in expired CO2 in mice in vivo by 300 per cent.
The same effect is obtained with slices of cerebral cortical grey matter from GHB‐treated rats, where the 1‐14C/6‐14C ratio is increased from 1.72 to 3.63, but not with homogenates of cerebral cortex, nor with slices of kidney or diaphragm.
GHB (500 mg/kg, intrapentoneally) specifically increases the activity of glucosed‐6‐phosphate dehydrogenase in vivo in rat and mouse whole brain by 27 per cent. The time course of this effect correlates with the sleeping time in both species.
The activity of glucose‐6‐phosphate dehydrogenase is not altered in vitro by high concentrations of GHB.
GHB stimulates O2 uptake by slices of cerebral cortical grey matter by 24 per cent, but it is not itself able to support respiration by the tissue.
It is proposed that GHB specifically increases the activity of the pentose phosphate pathway in brain, and that this effect is mediated by an increase in glucose‐6‐phosphate dehydrogenase activity.
CATIONIC COMPOSITION OF RAT CEREBRAL CORTEX SLICES. COMPARATIVE STUDY DURING DEVELOPMENT
Authors: Franck G. , Schoffeniels E. 
Published: October 2006

Abstract—

Slices of cerebral cortex isolated from 20‐day‐old rats, when incubated in an appropriate oxygenated saline, show only a slight increase in weight (± 0.4 per cent of initial fresh wt.). At 30 days, under the same conditions, this increase in weight is 12.4 per cent. This is similar to the value observed in adult animals (13.6 per cent).
Modifications of the cationic content of slices in the case of 20‐day‐old animals are very slight while in 30‐day‐old animals they are greater and similar to those observed with adults.
The inulin space of 20‐ and 30‐day‐old rats are the same. The swelling exhibited by the slices isolated from 30‐day‐old animals may reasonably be attributed to a cellular uptake of extracellular fluid. This is accompanied by an increase of the Naf concentration and by a decrease of the K+ concentration. The values observed are similar to those observed with adult rats.
Comparing our results with previous histological and histochemical data, it may be suggested that the modifications of cationic content, as well as the swelling of slices isolated from 30‐day‐old rats or adult animals, are solely attributable to changes affecting glial cells and more specifically the astrocytes.
TRANSPORT OF l‐TRYPTOPHAN INTO SLICES OF RAT CEREBRAL CORTEX1
Authors: Kiely Maureen , Sourkes T. L. 
Published: October 2006

Abstract—Slices of rat cerebral cortex, when incubated aerobically at 37°C in Krebs‐Ringer‐phosphate solution (pH 7.0) containing 10 mm glucose and 1.0 mm l‐tryptophan [1‐14C], accumulated tryptophan. Within the first 15 min of incubation the ratio of the concentration of the amino acid in the tissue to that in the medium reached 3.5:1. Uptake of tryptophan was linear for the first 30 min and attained a maximum concentration ratio (tissue:medium) of 6.5:1 within 60 min. The transport mechanism became saturated at 1.0‐3.0 mm tryptophan. Entry of the amino acid into the cortical cells was thereafter directly proportional to its initial concentration in the medium.The tissue: medium ratio at 15 min decreased significantly under the following experimental conditions: (1) lowering the incubation temperature to 0°C; (2) incubating under N2; (3) omitting glucose; (4) decreasing the Na+ concentration below 50 mm; (5) removing K+ from the medium; or (6) adding 1.0 mm NaCN or 0.1 mm protoveratrine B to the medium. These results provided evidence that the accumulation of tryptophan against its concentration gradient was an active process.The effects of a number of amino acids on the uptake of tryptophan were studied: of these, l‐phenylalanine, dl‐p‐chlorophenylalanine, l‐tyrosine, l‐DOPA, the branched chain aliphatic amino acids (l‐leucine, l‐isoleucine, l‐valine) and l‐glutamic acid were found to be the most potent inhibitors of tryptophan transport. Several tryptophan metabolites were tested; only l‐kynurenine inhibited the uptake of tryptophan.
AXONAL TRANSPORT IN NIGRO‐STRIATAL AND NIGRO‐THALAMIC NEURONS: EFFECTS OF MEDIAL FOREBRAIN BUNDLE LESIONS AND 6‐HYDROXYDOPAMINE1
Authors: Fibiger H. C. , Pudritz R. E. , McGeer P. L. , McGeer E. G. 
Published: October 2006

Abstract—Axonal transport was studied in two efferent projections of the substantia nigra: (1) the nigro‐striatal system; and (2) the nigro‐thalamic system. [14C]leucine was injected stereotaxically into the left substantia nigra of rats. At various intervals thereafter significant amounts of [14C]protein were found in the midbrain (which surrounded the injection site), hypothalamus, thalamus and corpus striatum on the injected side of the brain. By determining the temporal characteristics of the distribution of [14C]protein, axonal transport from the substantia nigra to the thalamus and corpus striatum could be inferred. Fast (approximately 50 mm/day) and slow (approximately 1 mm/day) rates of flow were evident in both systems. Either electrolytic lesions of the medial forebrain bundle or intraventricular pretreatment with 6‐hydroxydopamine (200 μg) produced a substantial decrease in the amount of labelled protein reaching the corpus striatum but not in that reaching the thalamus. The decrease following electrolytic lesions correlated significantly with the decrease in the activity of striatal tyrosine hydroxylase, but after 6‐hydroxydopamine the decrease in axonal transport was consistently less than the loss of striatal tyrosine hydroxylase. This difference indicated that a portion (perhaps as much as 20 per cent) of the nigro‐striatal neurons are non‐catecholaminergic. Finally, we present data which suggest that in contrast to effects on peripheral neurons, 6‐hydroxydopamine destroys the cell bodies as well as nerve terminals of adrenergic neurons in the central nervous system.
AXONAL MIGRATION OF VARIOUS RIBONUCLEIC ACID SPECIES ALONG THE OPTIC TRACT OF THE CHICK1
Authors: Bondy S. C. 
Published: October 2006

Abstract—The avian visual system has been used to study the axonal transport of RNA and protein. After monocular injection of radioactive uridine into 1‐day‐old chicks, a considerable amount of labelled RNA migrated along the optic tract to the optic tectum contralateral to the injected eye. This RNA was largely ribosomal, although it was contained in several subcellular fractions. The migration of RNA appeared to be a slow process. However, following monocular injection of radioactive proline, the migration of ribosomal protein was rapid. This discrepancy was resolved by examination of the kinetics of labelling of RNA and protein within the retina after intraocular injection of a mixture of labelled uridine and proline. Cytoplasmic RNA was labelled much more slowly than cytoplasmic protein. This lag in labelling of RNA could account for the delayed arrival of RNA at the contralateral optic lobe and suggests that ribosomes may travel rapidly along the axon.In other experiments, eyes were removed 4 days after the injection of labelled precursors. After a further 14 days, the remaining radioactivity in RNA and protein of contralateral optic lobes was 5–15% of that attributable to migration along the axon in control, unenucleated birds. Thus, the survival of the bulk of migrating macromolecules depends on the integrity of synaptic terminals. This observation suggests that both RNA and protein migrate within the axon rather than extra‐axonally, and that they remain largely within the nerve cells along the axons of which they are transported.
GABA TRANSPORT BY NERVE ENDING FRACTIONS OF CAT BRAIN1
Authors: Snodgrass S. R. , Hedley‐Whyte E. Tessa , Lorenzo A. V. 
Published: October 2006

Abstract— Nerve ending and mitochondrial fractions were prepared from cat cerebral cortex by differential and sucrose density gradient centrifugation. The isolated fractions were characterized morphologically and enzymatically and the nerve‐ending fraction was shown to be particularly rich in glutamate decarboxylase activity. The uptake of [3H] γ‐aminobutyric acid (GABA) was studied by trapping the particles on a Millipore filter.GABA uptake was not saturable over the concentration range studied (0.018 to 8000 μM. Tissue/medium ratios were consistently greater than 2·5, and uptake was significantly reduced by ouabain and iodoacetate, or by replacing sodium with lithium or choline chloride. GABA uptake was significantly inhibited by desmethylimipramine (DMI) with an IC50 of approx. 10–20 μM. GABA uptake was reduced by structurally similar amino acids lacking an α‐amino group, and also by methionine and phenylalanine, but not by short chain neutral amino acids.
AXONAL TRANSPORT OF CATECHOLAMINE SYNTHESIZING AND METABOLIZING ENZYMES
Authors: Wooten G. F. , Coyle J. T. 
Published: October 2006

AbstractThe 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

AbstractThe 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

AbstractSince 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

AbstractThe 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

Abstract—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

Abstract—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

Abstract—[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.