bluuebunny/crossref_metadata_2025 huggingface dataset:
ADENOSINE TRIPHOSPHATE CREATINE PHOSPHOTRANSFERASE OF RAT CEREBRAL CORTEX: EVIDENCE FOR A BIMODAL SUBCELLULAR LOCALIZATION*
Authors: Sullivan R. J. , Miller O. Neal , Sellinger O. Z.
Published: October 2006

—(1) ATP: creatine phosphotransferase of rat cerebral cortex is soluble to the extent of 57 per cent when the tissue is homogenized in 0.25 M‐sucrose and 80 per cent when distilled water is used for tissue dispersion. Among particulate fractions, the crude mitochondria] fraction contains the highest percentage of enzyme activity.

(2) Discontinuous sucrose gradient fractionation of the crude mitochondrial fraction yields about 55 per cent of the particulate activity in the nerve ending fractions and 24 per cent in the mitochondrial pellet.

(3) Rupturing of the nerve‐ending particles by a moderate osmotic shock designed to spare the mitochondria results in about 60 per cent of the ATP:creatine phosphotransferase becoming soluble, the remainder preserving the association with heavy particles, presumably mitochondria.

(4) Subfractionation of the microsomal fraction on a discontinuous sucrose gradient reveals that this particulate component of the enzyme is an adsorption artifact.

(5) The overall evidence points to at least two distinct subcellular localizations of the enzyme in rat brain cortex, a major soluble component and a particulate component. It has not been unequivocally shown whether the latter, in turn, reflects the presence of a single, mitochondrial component or whether the soluble matrix of the nerve ending particles represents a third locale for the enzyme.
THE FIXATION OF TETANUS TOXIN BY SYNAPTIC MEMBRANES
Authors: Mellanby Jane , Whittaker V. P.
Published: October 2006

—The ability of subfractions of disrupted synaptosomes to bind tetanus toxin has been studied. Synaptic vesicles had little toxin‐fixing capacity, but a fraction believed on morphological appearance and enzymic composition to be rich in external synaptosome membranes had a toxin‐fixing capacity about 10 times that of the synaptic vesicles and over twice that of the initial brain homogenate. Mitochondria also had a low toxin‐fixing capacity and other membrane fractions had an intermediate value. The results are discussed in relation to the known role of ganglioside in fixing toxin.
PROTEIN SYNTHESIS IN NORMAL AND SCRAPIE MOUSE BRAIN
Authors: Millson G. C. , Hunter G. D.
Published: October 2006

Abstract—

Damage to the brain as a result of an intracerebral injection of physiological saline does not appreciably affect the rate of protein synthesis in mouse brain. The in vivo and in vitro incorporation of labelled amino acids into mitochondria and their in vivo incorporation into nuclei, microsomes, nerve ending particles, myelin and cell sap were compared in normal and scrapie‐affected mice. No significant differences were found.
EFFECT OF ACUTE CYANIDE INTOXICATION ON THE ACTIVE TRANSPORT OF AMINO ACIDS IN BRAIN SLICES*
Authors: Levi G. , Amaducci L.
Published: October 2006

Abstract—

(1) Acute hypoxia was produced in adult rats by cyanide inhalation and the effect on the active transport of amino acids was studied in brain slices.

(2) Initial and steady‐state accumulation of amino acids and rates of amino acid exit were identical in brain slices from control and treated animals when a glucose‐containing incubation medium was used.

(3) When the incubation was carried out in a glucose‐free incubation medium, the inhibition of initial and steady‐state accumulation and the stimulation of amino acid exit observed in control slices were significantly reduced or abolished in slices from treated animals.

(4) Tissue swelling, size of ‘inulin space’ and glucose consumption did not differ in the two groups of animals.

(5) Also the respiration rate was identical in slices from control and treated animals incubated in the presence of glucose. In the absence of added substrate, brain slices from treated animals consumed 15‐20 per cent more oxygen than control slices.

(6) A possible correlation between the effects observed on amino acid transport and on respiration is suggested. The reasons why cyanide given in vivo or added in vitro have different effects on amino acid transport in brain slices are discussed.
SODIUM STIMULATED [14C]ADENOSINE DIPHOSPHATE‐ADENOSINE TRIPHOSPHATE EXCHANGE ACTIVITY IN BRAIN MICROSOMES
Authors: Stahl W. L.
Published: October 2006

Abstract—

An ADP‐ATP exchange reaction was studied in NaI‐treated microsomes from rat brain. At low concentrations of MgCl2 a nucleotide exchange reaction, elicited in the presence of Na+, had an absolute specificity for ATP. The reaction was stimulated by oligomycin and inhibited by ouabain and EDTA. It is probable that this Na+‐stimulated ADP‐ATP exchange reaction is a component of the Na‐K ATPase system.
SEIZURE THRESHOLD, ADRENALECTOMY AND SODIUM‐POTASSIUM STIMULATED ATPase IN RAT BRAIN*1
Authors: Gallagher B. B. , Glaser G. H.
Published: October 2006

Abstract—

Adrenalectomy in the rat was shown to lower seizure threshold measured with the volatile convulsant hexafluorodiethyl ether. Although the expected hyponatraemia and hyperkalaemia were demonstrated in the adrenalectomized rats, there was no associated alteration in Na‐K stimulated Mg‐ATPase activity either in the whole rat brain or in a microsomal fraction. These results in brain tissue are contrasted with the marked decrease in this enzyme that occurs in kidney tissue of the rat following adrenalectomy. It was suggested that the activity of the enzyme system responsible for active cation transport responds directly in proportion to the work of active transport required by the individual tissue.
INTERACTION OF EXCITATORY AND DEPRESSANT AMINO ACIDS IN THE FROG RETINA
Authors: KISHIDA K. , NAKA K.‐I.
Published: October 2006

Abstract— (1) Application of excitatory or depressant amino acids (concentrations from 10−6 to 10−2m) could modify response patterns of the retinal ganglion cells to photic stimulus. Excitatory amino acids gave rise to spontaneous discharge while depressant amino acids inhibited spike discharge in response to test flashes.

(2) Application of excitatory amino acids of more than 10−3m resulted in irreversible termination of spike discharges while recovery was always observed in the case of depressant amino acids even when the concentration of the applied solution was as high as 10−3m. No effect was observed when one exciting and one depressant amino acid were properly combined.

(3) There is a mixture of four amino acids (two excitatory and two depressant) which could enhance the spike discharge in response to test flashes without giving rise to spontaneous firing.

(4) It is implied that proper balance of excitatory and depressant amino acids is important in regulating the excitability of a number of neurons.
ACETYL TRANSPORT MECHANISMS IN THE NERVOUS SYSTEM. THE OXOGLUTARATE SHUNT AND FATTY ACID SYNTHESIS IN THE DEVELOPING RAT BRAIN*
Authors: D'Adamo Amedeo F. , D'Adamo Ann P.
Published: October 2006

Abstract Radioactive acetyl groups and lipids are produced from dl‐[5‐14C]glutamate. Degradation studies indicate that approximately 90 per cent of the radioactivity is localized in the original carboxyl groups of the two carbon unit. Since these results are shown not to be due to a 14CO2 fixation, it is concluded that the oxoglutarate shunt as an acetyl group transport system is functional in brain.

The highest ratio of fatty’acid activity/CO2 activity in this pathway is found in the newborn rat brain and steadily decreases with development. This pattern is observed with incubations of brain slices with labelled glutamate or citrate and is similar to the changes observed in the activity of the citrate cleavage enzyme with brain maturation.

In contrast to the previous studies with liver preparations, the conversion of [2‐14C]‐ and [5‐14C]glutamate to fatty acids is relatively small. This is particularly true during the period of maximal lipid synthesis.
LIQUID CATION EXCHANGE EXTRACTION OF CHOLINOMIMETIC ACTIVITY FROM BRAIN
Authors: Johnston G. A. R. , Lloyd Helen J. , Stone Nancy
Published: October 2006

Abstract— Liquid cation exchange extraction methods have been applied to the extraction of cholinomimetic activity from subcellular fractions, rich in nerve‐ending particles, derived from rat brain homogenates. The results obtained indicate that the activity is due largely to acetylcholine or closely related materials of similar basic strength, and that non‐basic materials, such as acetyl‐l‐carnitine, appear to contribute little to the observed activity.
DIFFERENCES IN THE NUCLEAR RIBONUCLEIC ACID CONTENT IN DIFFERENT AREAS OF THE HUMAN ADULT AND FOETAL BRAIN*
Authors: Hoch‐Ligeti Cornelia , Stutzman E. , Gruenwald C.
Published: October 2006

Abstract— Four different areas of ten brains from adults in the age group between 44 and 74 years and two areas of six foetal brains were studied.

The cellular density was similar in the different areas of the brain of adult man; it averaged 11.9 × 107/g wet tissue. The number of neurons per g wet tissue varied from 2.22 × 107 in the cortex to 0.15 × 107 in the centrum semiovale.

In the brain of adults the overall RNA content of nuclei was higher for the cortex than for the corpus callosum or the centrum semiovale.

The RNA content of neuronal nuclei was higher than that of non‐neuronal nuclei.

In the brain of foetuses the nuclear density was higher than in adults. The DNA content of a nucleus in foetal brain was 2–3 times as high as in adult brain and it approached adult values with increasing maturity.
THE INTRASPINAL DISTRIBUTION OF SOME DEPRESSANT AMINO ACIDS
Authors: Johnston G. A. R.
Published: October 2006

Abstract— —Six known depressant amino acids were found in extracts of feline spinal grey matter: α‐alanine, cystathionine, GABA, glycine, serine and taurine.

Of these, glycine has the distribution within the nervous system anticipated of a sub‐stance whose main function is as a spinal inhibitory transmitter at strychnine‐sensitive synapses, GABA being a likely transmitter candidate at any strychnine‐insensitive spinal inhibitory synapses.

The intraspinal distributions of α‐alanine, cystathionine, serine and taurine reveal little to indicate that a synaptic role is a major function of these amino acids.
SYNTHESIS OF NUCLEIC ACIDS IN THE SCHWANN CELLS AS THE EARLY CELLULAR RESPONSE TO NERVE INJURY1
Authors: Oderfeld‐Nowak Barbara , Niemierko Stella
Published: October 2006

Abstract— The early effect of mechanical injury of the sciatic nerve in cats and rats on the amount of nucleic acids and on the number of Schwann cells was studied.

The content of RNA and DNA increased at both ends of a severed nerve as early as 2 hr after operation; at 8 hr and up to 24 hr, their level was about twice as high as at the beginning of experiment. The increase in nucleic acids seemed to be chiefly due to their biosynthesis in the Schwann cells although the possibility of a contribution of axonal RNA must also be taken into consideration. The division of Schwann cell nuclei was observed not earlier than 36 hr after operation. The injury stimulates the synthesis of nucleic acids not only in the Schwann cells directly damaged, but also in those from neighbouring internodes.

The increase in DNA and RNA observed 24 hr after a fresh lesion had been made in a degenerating nerve was smaller than the increase observed 24 hr after cutting or crushing a normal nerve.
ISOLATION AND CHARACTERIZATION OF GLYCOSAMINOGLYCANS IN BRAIN OF DIFFERENT SPECIES
Authors: Singh M. , Chandrasekaran E. V. , Cherian R. , Bachhawat B. K.
Published: October 2006

Abstract— The uronic acid‐containing glycosaminoglycans present in the brains of rat, monkey, chicken, sheep and rabbit were isolated into various fractions by combining the cetyl pyridinium procedure and DEAE‐Sephadex column chromatography. The analyses of the fractions show that hyaluronic acid, chondroitin‐4‐sulphate, chondroitin‐6‐sulphate, heparan sulphate and a testicular hyaluronidase‐resistant galactosamine‐containing GAG are present in the brain of all the species studied. Hyaluronic acid is the major GAG (33–41 per cent). Chondroitin‐4‐sulphate (19–35 per cent), and heparan sulphate (11–19 per cent), are the next prominent GAGs, in all the species except chicken. The results indicate the similarity in the pattern of GAGs in the brain of all the species.
SUBCELLULAR DISTRIBUTION AND CHEMICAL NATURE OF THE RECEPTOR FOR 5‐HYDROXYTRYPTAMINE IN THE CENTRAL NERVOUS SYSTEM1
Authors: Fiszer Sara , DE Robertis E.
Published: October 2006

Abstract— In vitro binding experiments with 5‐hydroxy[14C]tryptamine (3.3 × 10−6 M) were carried out on subcellular fractions of the cat brain. The highest specific activity was observed in some fractions of nerve‐ending membranes isolated from the hypothalamus, basal ganglia, and gray areas of the mesencephalon. The specificity of this high affinity binding was demonstrated by competition with reserpine, butanolamide of lysergic acid, and desmethylimipramine. With butanol‐water extraction the [14C]5‐HT was found in the butanol while the gangliosides were separated in the water phase. Several experiments with thin layer and column chromatography suggest that in the organic phase the [14C]5‐HT is not bound to the lipids but to a special proteolipid. This proteolipid is different from that found in myelin and has similar chromatographic properties to that previously observed in the proteolipid which binds d‐[14C]tubocurarine in nerve‐ending membranes of the cerebral cortex.
SUBCELLULAR DISTRIBUTION OF ENDOGENOUS AND [3H] γ‐AMINOBUTYRIC ACID IN RAT CEREBRAL CORTEX
Authors: Neal M. J. , Iversen L. L.
Published: October 2006

Abstract— Slices of rat cerebral cortex were labelled by incubation with [3H]γ‐aminobutyric acid (GABA) and homogenized in isotonic sucrose. The subcellular distributions of endogenous GAB A, [3H]GABA and glutamate decarboxylase (GAD) were studied by density gradient centrifugation. The subcellular distributions of the labelled and endogenous amino acid were remarkably similar, indicating that [3H]GABA is taken up into the endogenous GABA pool. About 40 per cent of both endogenous and [3H]GABA were recovered in particles which were tentatively identified as synaptosomes from their equilibrium density and sensitivity to osmotic shock. In slices labelled with [3H]GABA and [14C]α‐aminoisobutyric (AIB) acid, significantly more [3H]GABA was recovered in paniculate fractions than [14C]AIB. About 80 per cent of the enzyme GAD was also recovered in the same particle fractions which contained [3H]GABA and endogenous GABA. Evidence is presented which suggests that a loss of particle‐bound GABA occurs during subcellular fractionation procedures.
PROTEIN METHYLATION IN RAT BRAIN IN VITRO
Authors: Paik W. K. , Kim S.
Published: October 2006

Abstract— Protein‐methylation activity in various organs of the rat was studied with S‐adenosyl‐L‐[methyl‐14C]methionine ([methyl‐14C](SAM) as methyl donor. Activity of the enzyme was highest in brain and lowest in liver. Histones comprised approximately 20 per cent of the total radioactivity incorporated, and lysine‐rich histone was the most active. Analysis of amino acids of the methylated proteins of rat brain showed arginine to be the amino acid most extensively methylated, but some methylation occurred in lysine residues. An additional [methyl‐14C]‐labelled amino acid was found near histidine on the amino acid column chromatogram.
INTERRELATIONSHIPS AMONG THE ETHANOLAMINE PHOSPHATIDES IN MYELINATING RAT BRAIN1
Authors: JOFFE S.
Published: October 2006

Abstract— —The ethanolamine phosphatide fraction was isolated from rat brain at 17, 19, and 22 days of age. Analysis by gas‐liquid chromatography of the liberated fatty aldehydes and alkyl glyceryl ethers demonstrated a chain length composition quite distinct from that of the fatty acids in the comparable 1(3)‐position of the diacyl phosphatides. [1‐14C]‐Acetate was administered intraperitoneally to 17‐day‐old rats. With the exception of the polyunsaturated fatty acids, isotope was readily incorporated into the individual side chains of the 1‐ and 2‐positions of the glycerol moiety. Time studies revealed no readily discernible precursor‐product relationships among the linkages in question. Therefore, although the long chain precursors for the alkenyl and alkyl ethers may be related by biosynthetic interconversion, the isotope data are suggestive of independent pathways of biosynthesis for the alkenyl ether, alkyl ether, and ester linkages.
FAST AND SLOW PHASES OF AXOPLASMIC FLOW IN VENTRAL ROOT NERVE FIBRES1
Authors: Ochs S. , Johnson J.
Published: October 2006

Abstract—

The pattern of activity found in ventral roots removed at different times after seventh lumbar and first sacral cord injections of [3H]leucine gave evidence for fast and slow phases of axoplasmic flow. An intra‐axonic location was shown for the fast flow by the block of downflow produced by freezing a narrow region of the ventral root, by reduction of downflow on preinjection of puromycin into the cord and by radioautography of ventral roots. Separate mechanisms appear to be required to account for the fast and slow phases of axoplasmic flow.
METABOLIC INVESTIGATIONS OF EPILEPTIC SEIZURES
Authors: Wiechert P. , Göllnitz G.
Published: October 2006

Die Konzentration der freien Aminosäuren im Gehirn von Ratten vor und während experimentell ausgelöster cerebraler Krampfanfälle wird den von Kontrollratten gegenübergestellt. Die Konzentration der Glutaminsäure ist in alien präkonvulsiven und tonischen Phasen eines cerebralen Anfalls signifikant erhöht. Auch die eng mit dem Stoffwechsel der Glutaminsäure verbundenen Aminosäuren Alanin, γ‐Aminobuttersäure, Asparaginsäure und Glutamin zeigen eine deutliche Konzentrationszunahme.

Insbesondere der Konzentrationsanstieg der Glutaminsäure wird als Folge der bereits früher beschriebenen veränderten Enzymaktivitäten im Glutamatstoffwechsel (Wiechert und Göllnitz, 1969) angesehen. Die Konzentration der γ‐Aminobuttersäure kann nicht in gleichem Maße ansteigen, und das normale Verhältnis beider Aminosäuren ist in unphysiologischer Weise verschoben. Die Verschiebung dieses Gleichgewichtes als Ursache der Auslösung des Anfalls wird diskutiert.

The concentration of free amino acids in the brain of rats prior to and during experimental cerebral seizures was compared with that of controls. The concentration of glutamic acid was significantly increased in all preconvulsive and tonic phases of the cerebral seizures, which was also true for alanine, γ‐aminobutyric acid, aspartic acid and glutamine, which are closely connected with the metabolism of glutamic acid.

The increase in the concentration of glutamic acid is considered to be a consequence of altered activities of enzymes involved in glutamate metabolism. The concentration of γ‐aminobutyric acid did not increase in the same proportion and the normal ratio of these two amino acids was shifted in abnormal stores in favour of the former. The relationship between this shift and the cause of the convulsions is discussed.
DISTRIBUTION AND UPTAKE OF AMINO ACIDS IN VARIOUS REGIONS OF THE CAT BRAIN IN VITRO
Authors: Battistin L. , Grynbaum Alice , Lajtha A.
Published: October 2006

—(1) The levels of the free amino acids were determined in five areas of the cat brain. The regional pattern was heterogeneous and fairly characteristic for each compound.

(2) The uptakes of α‐aminoisobutyric acid, taurine, d‐aspartic acid, and l‐histidine were measured in incubated slices from 31 regions of the cat CNS. Differences in uptake were found among the various areas; the regional pattern of uptake was different for each amino acid. The initial rate of uptake (5 min incubation) very often paralleled the rate at equilibrium (90 min incubation).

(3) The regional correlation between distribution in vivo and uptake in vitro was good for aspartate, less so for histidine, and poor for taurine.

(4) It is concluded that regional heterogeneity in exit processes, available energy, cell density, or protein content is unlikely to have decisive influence in determining regional differences in distribution and transport of metabolites; it seems that influx is the most important factor.
CEREBROSIDE‐SULPHATASE AND ARYLSULPHATASE A DEFICIENCY IN METACHROMATIC LEUKODYSTROPHY (ML)
Authors: Jatzkewitz H. , Mehl E.
Published: October 2006

Abstract— Cerebroside‐sulphatase, arylsulphatase A and B and acid phosphatase activities were determined in renal cortex, liver, and cerebral white matter, obtained at autopsy from seven patients with metachromatic leukodystrophy (ML) and nine controls. It was shown that both arylsulphatase A and cerebroside‐sulphatase activity were reduced to the limit of detection (1–6 per cent of that of the controls) in all ML‐tissues.

The quantitative evaluation of the sulphatide level in ML‐demyelinated cerebral white matter and in kidney showed that there was no relationship between the amount of accumulated sulphatide and the duration of illness or the age at death (up to the age of 20). If there should exist any relationship between the sulphatide level and residual enzyme activity, then this residual activity must be beyond the sensitivity of the enzymic assay.

This point, and the detailed sequence of the pathological events in brain leading from a deficient cerebroside‐sulphatase activity to a pronounced demyelinating disease, sparing grey matter, are discussed.
CORRELATION BETWEEN DECREASES IN BRAIN γ‐AMINOBUTYRIC ACID LEVELS AND SUSCEPTIBILITY TO CONVULSIONS INDUCED BY HYPERBARIC OXYGEN1
Authors: Wood J. D. , Watson W. J. , Murray G. W.
Published: October 2006

Abstract— The susceptibility of mice to seizures at hyperbaric pressures of oxygen (OHP) was placed on a quantitative basis and compared with the corresponding rate of decrease in brain GABA concentration. The influence of small amounts of carbon dioxide in the breathing mixture on these effects of OHP was also determined. A correlation between the rate of decrease in GABA and susceptibility to seizures was shown to exist not only over the varying oxygen pressures and varying concentrations of carbon dioxide used in the present experiments out also over varying animal species (a previous study). The critical oxygen pressure for decreases in brain GABA to occur was shown to be 30 p.s.i.g. This value agreed closely with the well documented critical pressure necessary to produce seizures in both animals and man. The probability that lowered brain GABA levels play a major role in the etiology of OHP convulsions was discussed.
PROTEIN SYNTHESIS IN VISUAL CELLS OF LIMULUS
Authors: Burnel M , Mahler H. R , Moore W. J
Published: October 2006

Abstract— The incorporation of l‐[4,5‐3H]leucine into the primary visual cells of lateral eyes of Xiphusura polyphemus (Limulus) was followed by electron microscopic radio‐autography, while protein synthesis in the tissue surrounding the primary cells was measured by scintillation counting of the extracted protein. In the primary cells, the incorporation of radioactivity during 24 h into the rhabdomal membranes was 10–20 times greater in dark than in light, and was especially high in eyes that had been exposed to light before a period of incorporation in the dark. In tissue adjacent to the primary cells, protein synthesis was about 50 per cent greater in eyes exposed to light. These results are interpreted in terms of the photochemistry of Limulus rhodopsin and the competition for ATP between sodium‐pump and protein‐synthetic mechanisms.
EFFECTS OF SPREADING CORTICAL DEPRESSION ON THE INCORPORATION OF [14C]LEUCINE INTO PROTEINS OF RAT BRAIN
Authors: Křivánek J
Published: October 2006

Abstract— Incorporation of dl‐[1‐14C]leucine into proteins of the cerebral cortex of the rat was measured during spreading cortical depression (CSD) evoked by a single topical application of 25% (w/v) KCI. Maximal inhibition (42 per cent) of the rate of incorporation occurred 1 hr after application of KCI. Spreading depression of 2–3 hr duration was associated with 22 per cent and 13 per cent decreases, respectively, of incorporation of labelled leucine. Specific activity of the free pool leucine was not decreased during CSD but appeared to be higher than controls at 20 min after initiation of CSD. The specific activity of the total free pool amino acids was also increased at 10, 20, 60 and 120 min after application of KCI.

The inhibitory effect of CSD on incorporation of leucine into proteins was uniformly distributed among the crude mitochondrial, microsomal and soluble subcellular fractions from brains of adult animals, while in fractions from 25‐day old animals there appeared to be relatively more inhibition in the crude mitochondrial fraction.
NEUROCHEMICAL AND STRUCTURAL STUDIES ON THE MECHANISM OF ACTION OF HEMICHOLINIUM‐3 IN CENTRAL CHOLINERGIC SYNAPSES
Authors: De Lores Arnaiz Georgina Rodríguez , Zieher L. M. , De Robertis E.
Published: October 2006

—The action of hemicholinium‐3 (HC‐3) on the cerebral cortex of the rat was studied after subarachnoidal administration. There was a marked decrease of content of ACh in nerve endings and especially in the fraction containing synaptic vesicles, despite the fact that the number of synaptic vesicles was not reduced, as judged by electron microscopy, by the rate of incorporation of ortho [32P]phosphate, and by the phosphorus content of the phospholipids of the isolated synaptic vesicles. There was a close association of [l4C]HC‐3 and of monoaminoxidase, which indicated that the drug was preferentially bound to mitochondria. Experiments indicating that HC‐3 could be acetylated suggested that this drug may compete with choline not only for entry but also for acetylation.
REVERSIBLE CHANGES IN GLUTAMINE LEVELS IN THE CAT CEREBRAL CORTEX EVOKED BY AFFERENT ELECTRICAL STIMULATION AND BY ADMINISTRATION OF PENTAMETHYLENETETRAZOLE (PENTYLENETETRAZOL)
Authors: DOBKIN J.
Published: October 2006

—1. Levels of glutamine and glutamate were measured in cat cerebral cortex rapidly frozen in situ after 30 sec of afferent electrical stimulation (AES) of the contralateral brachial plexus. A substantial decrease in glutamine and a minor one in glutamate were found as compared to the ipsilateral cortex. The fall in glutamine was found to be reversed very shortly after break of the current.

2. Glutamine levels of the cortex determined after rapid freezing in situ were found to fluctuate with the diverse stages of periodic convulsions induced by pentylenetetrazol (PTZ): glutamine was substantially decreased during the initial part of the first clonictonic convulsion, it returned to the normal value in its termination stage and remained so at the commencement of the interictal recovery period, dropping again shortly before the onset and in the course of the second convulsion. The second drop in glutamine was accompanied by a decrease of glutamate. In the comatose state which followed convulsions, both glutamine and glutamate were again at their original concentrations.

3. The results suggest that the view of the metabolic stability of brain glutamine under cerebral stimulation—based on past reports—should be modified in the sense that glutamine is labilized by excitation, but this effect is obscured by the counteracting process of synthesis de novo.

4. The significance of the data reported here, in relation to the incidence and termination of convulsions, as well as the mechanisms which may be involved in the observed fall and restitution of the level of cerebral glutamine, are discussed.
SUBCELLULAR DISTRIBUTION OF AROMATIC AMINO ACID TRANSAMINASES IN RAT BRAIN
Authors: Semba T. , Civen M.
Published: October 2006

Abstract— The subcellular distributions of tyrosine transaminase, DOPA transaminase, tryptophan transaminase and 5‐hydroxytryptophan (5‐HTP) transaminase were studied in rat brain.

For all of these transaminases 60‐81 per cent of the total activities were found in the crude mitochondrial fraction. Tyrosine transaminase was the most active enzyme.

Tyrosine transaminase and DOPA transaminase had very similar distributions in all fractions, but the distribution of tryptophan transaminase and 5‐HTP transaminase differed in the microsomal (Mic) and synaptic vesicle (M2) fractions. Only 5‐HTP transaminase was highly concentrated in the M2 fraction.

DOPA transaminase was inhibited by dopamine and 5‐HT, but these compounds had no effect on 5‐HTP transaminase. Both enzymes were completely inhibited by m‐hydroxybenzoyloxyamine.
REGIONAL DISTRIBUTION OF COLCHICINE‐BINDING (MICROTUBULAR) PROTEIN IN THE RAT BRAIN1
Authors: Dahl D. R. , Redburn D. A. , Samson F. E.
Published: October 2006

Abstract—

The relative concentrations of microtubular protein (tubulin) in regions of rat brain were determined by taking advantage of its specific property of binding colchicine. In comparison with other tissues, all regions of the brain were rich in tubulin. The cerebral cortex, thalamus and hypothalamus had essentially the same concentration. The cerebellum and brain stem had a lower concentration (about 60 per cent of the cortical level). Although the functional significance of these differences is not clear, they may relate to two proposed functions of microtubules–cytoskeleton and cytoplasmic transport. The complex geometry of neurons and many glial cells with ramified processes must require extensive systems for maintaining shape and an active cytoplasmic transport.
BINDING OF MUSCARONE BY EXTRACTS OF HOUSEFLY BRAIN: RELATIONSHIP TO RECEPTORS FOR ACETYLCHOLINE
Authors: Eldefrawi A. Toppozada , O'Brien R. D.
Published: October 2006

Abstract—

The supernatant fluid fraction isolated by centrifugation from a homogenate of heads of houseflies bound muscarone reversibly, with a binding constant of 2·4 × 10−6m and an amount of 70 nmol/g of protein. Studies with 28 drugs demonstrated strong blockade by the 17 cholinergic agents, suggesting both nicotinic and muscarinic characteristics in the mode of binding. The binding appeared to involve acetylcholine receptors.
PIG BRAIN GLUTAMINASE: PURIFICATION AND IDENTIFICATION OF DIFFERENT ENZYME FORMS
Authors: SVENNEBY G.
Published: October 2006

—Pig brain glutaminase (EC 3.5.1.2 L‐glutamine amidohydrolase) has been purified about 5000‐fold from acetone powder. Glutaminase exists in different molecular forms, dependent on the ionic composition of the buffer. The three main forms are similar to those of kidney glutaminase and therefore called the tris‐HCl enzyme, the phosphate enzyme, and the phosphate‐borate enzyme. The sedimentation coefficients, as estimated by sucrose gradient technique, are 7·3, 8·7, and 53, respectively. Glutaminase has a pH optimum of about 9, but the pH curves of the tris‐HCl enzyme and the phosphate‐borate enzyme have different shapes. The apparent pK1 of the tris‐HCl enzyme‐substrate complex is similar to pK2 of inorganic phosphate, the apparent pK2 of both the tris‐HCl and the phosphateborate enzyme complexes is similar to pK2 of glutamine. By use of the electron microscope we were able to see the phosphate‐borate enzyme.
THE INCORPORATION OF ISOTOPIC CARBON 14C INTO THE CEREBRAL GLYCOGEN OF NORMAL AND X‐IRRADIATED RATS
Authors: Lundgren P. R. , Miquel J.
Published: October 2006

Abstract—

Maximal incorporation of 14C from labelled glucose into cerebral glycogen of the rat occurred at 3‐6 h following intravenous injection of the precursor. A reduction of the rate of glycogen breakdown is the most likely cause of the glycogen accumulation observed in rat brain following exposure to 10 krad of X‐radiation.
FURTHER STUDIES ON THE EFFECTS OF BLOCKING AGENTS ON PROTEIN SYNTHESIS IN GOLDFISH BRAIN1
Authors: Lim R. , Brink J. J. , Agranoff B. W.
Published: October 2006

Abstract— In further experiments on the effects of antibiotic agents on protein synthesis in the goldfish brain, doses of intracranially‐injected puromycin or acetoxycycloheximide higher than those previously employed did not hasten the onset of inhibition of incorporation of intraperitoneally‐injected [3H]leucine into brain protein.

The antibiotic‐resistant incorporation was not due to the presence of labelled blood protein in the brain. After the intracranial injection of labelled puromycin, the appearance of radioactivity in the acid‐soluble fraction of brain was blocked by acetoxycycloheximide. Repeated daily intracranial or intraperitoneal injections of puromycin were lethal, and acetoxycycloheximide was not protective, indicating that peptidyl‐puromycin was present in the brain but did not account for the lethality of puromycin. Behavioural experiments argued against but did not totally exclude the possibility that peptidyl‐puromycin was responsible for the amnestic effect of puromycin. Puromycin aminonucleoside, O‐methyl tyrosine and 5‐guanylyl methylenediphosphonate had little or no effect on protein synthesis in brain, but gougerotin was slightly inhibitory.
Preparation, properties and fractionation of the nuclear deoxyribonucleic acid from guinea pig brain
Authors: Mori K. , Yamagami S. , Akahani Y. , Kawaktta Y.
Published: October 2006

Little work has been done on the chemical and physical properties of brain nuclear DNA. Recently Du Buy, Mattern and Riley (1966) described the heat denaturation of mouse brain nuclear DNA, which apparently differs from the related mitochondrial DNA and the various protozoal DNA's tested. For such studies, it is essential to prepare the nuclear DNA from brain tissues in a native and highly polymerized state. In this brief communication preparation procedures of the native DNA from isolated brain nuclei are described, and some physical and chemical properties are given.
EFFECTS OF POTASSIUM ON INDICATOR SPACES AND FLUXES IN SLICES OF BRAIN CORTEX FROM ADULT AND NEW‐BORN RATS
Authors: Schousboe A. , Hertz L.
Published: October 2006

—Inulin, sucrose and chloride spaces were measured in slices of brain cortex from adult and from new‐born rats incubated in‘balanced', potassium‐rich and sodium‐rich media. The efflux of the radioactive markers was followed in the two first media and the following results were obtained:

(1) In brain slices from new‐born rats inulin and sucrose spaces were of identical magnitude (35 per cent). The space magnitude was essentially unaffected by excess potassium. The chloride space was somewhat larger than the inulin (sucrose) space, and the difference increased continuously but relatively slightly with the external potassium concentration. By far the largest amount (i.e. about 90 per cent) of the efflux of radioactive inulin, sucrose and chloride occurred from a rapidly exchanging compartment during incubation in both ‘balanced’ and potassium‐rich media.

(2) In brain slices from adult rats the inulin space (35 per cent) was significantly smaller than that of sucrose (50 per cent) and of chloride (65 per cent); it seemed to represent the extracellular space relatively well although 10 per cent of the efflux occurred from a slowly exchanging (probably intracellular) compartment. High concentrations of potassium led to a reduction of the inulin space which was probably a result of the concomitant intracellular swelling. The hyperosmolarity per se did not affect the space magnitude, but an increase of the sodium concentration exerted a competitive inhibition of potassium effects on the inulin space. Of the sucrose efflux, 20 per cent occurred from a slowly exchanging compartment in both ‘balanced’ and potassium‐rich media, and 30 per cent of the chloride exchanged with this compartment when the tissue was incubated in a ‘balanced’ medium. An increase of the external potassium concentration caused a drastic increase of the chloride space and a reduction of the slowly exhanging fraction of chloride efflux to less than 10 per cent.
REGULATION OF PYRUVATE KINASE IN THE RAT CEREBRAL CORTEX1
Authors: Schwark W. S. , Singhal R. L. , Ling G. M.
Published: October 2006

—The distribution of pyruvate kinase (ATP: pyruvate phosphotransferase; EC 2.7.1.40) in several areas of the central nervous system, the ontogenic changes in the cerebro‐cortical enzyme, and its modulation by certain metabolites were investigated in the rat. No significant differences in activity of pyruvate kinase in different regions of the nervous system were detected when activity was expressed per g of tissue. Studies on the ontogeny of pyruvate kinase in cerebral cortex revealed extremely low levels of enzymic activity at birth. A two‐fold increase occurred between 1 and 20 days of postnatal age, with a further two‐fold increase between 20 and 60 days of age.

l‐Phenylalanine, when added directly into the reaction mixture, produced a dose‐dependent inhibition of cerebro‐cortical pyruvate kinase; a similar inhibition of the enzyme activity was observed with copper. The inhibition by l‐phenylalanine and copper was prevented and reversed by l‐alanine. Although the cerebro‐cortical enzyme was resistant to thermal inactivation at 37°C, incubation of the enzyme preparation at 55°C for 60 min resulted in approximately 60 per cent inhibition of its activity. Preincubation with l‐alanine provided partial protection against thermal inactivation of the enzyme. Although l‐alanine exerted no effect on the non‐competitive inhibition of pyruvate kinase produced by calcium, such inhibition was prevented and reversed by EDTA. The sulphydryl inhibitor, P‐chloromercuribenzoate, produced a dose‐dependent inhibition of cerebro‐cortical pyruvate kinase, whereas addition of penicillamine resulted in a slight activation of the enzyme. Although inhibition of pyruvate kinase by P‐chloromercuribenzoate was unaffected by l‐alanine, penicillamine effectively prevented and reversed the inhibition produced by P‐chloromercuribenzoate.
CHOLINE ACETYLTRANSFERASE AND ACETYLCHOLINESTERASE IN CULTURED BRAIN CELLS FROM CHICK EMBRYOS
Authors: Werner I. , Peterson G. R. , Shuster L.
Published: October 2006

—Dissociated cells from brains of 7‐day chick embryos were grown in primary culture for as long as 20 days. Many of the plated cells grew out long processes. Others, which proliferated rapidly, formed a confluent layer of flat cells after 4‐6 days. Total DNA and protein increased five‐fold, and activity of choline acetyltransferase (EC2.3.1.6) increased about 40‐fold in 20 days. Acetylcholinesterase (EC3.1.1.7) increased three‐fold by the fourth day of culture and then declined. The pattern of increase for choline acetyltransferase was similar to that for the in vivo development of the enzyme.

l‐Thyroxine, cyclic AMP (adenosine‐3′,5′‐monophosphate) or theophylline promoted increased levels of both enzymes by 30‐200 per cent. l‐Thyroxine also increased the activity of acetylcholinesterase in vivo by 40 per cent. When overgrowth by flat cells was prevented by the addition of 10‐3m‐5‐flourouracil, there was a decrease in the activity of choline acetyltransferase and an increase in the activity of acetylcholinesterase in comparison to control activities. The addition of 10‐3m‐morphine or cocaine produced a 30 per cent elevation in the activity of choline acetyltransferase, but this effect could be mimicked with equimolar concentrations of ammonium ion.
MEMBRANE FRAGMENTS FROM MYELIN TREATED WITH DIFFERENT DETERGENTS
Authors: McIlwain D. L. , Graf L. , Rapport M. M.
Published: October 2006

Abstract—

Bovine CNS myelin treated with cationic, anionic and non‐ionic detergents yielded fragments which did not sediment in water at 56,500 g for 15 min. Substantial chemical and immunological differences were observed among the myelin fragments produced by these detergents. The chemical and immunological characteristics of such membrane products were also dependent upon the concentration of detergent. These and similar findings with other biological membranes emphasize the difficulties in using detergents to obtain and examine proposed subunit structures.
GLYCOL SULPHATE ESTER FORMATION FROM [14C]NORADRENALINE IN BRAIN AND THE INFLUENCE OF A COMT INHIBITOR
Authors: Sugden R. F. , Eccleston D.
Published: October 2006

Abstract—

A method is described allowing the identification and separation of the sulphate esters of the glycol metabolites of [14C]noradrenaline injected into the lateral ventricle of the rat. The esters of both the 3,4‐dihydroxy derivative and the 3‐methoxy‐4‐hydroxy derivative are formed in substantial amounts. It is suggested that the quantity of the former may have been underestimated in the past. Contemporaneous administration of pyrogallol, a catechol‐O‐methyl transferase inhibitor, with [14C] noradrenaline leads to a considerable fall in 3‐methoxy‐4‐hydroxyphenylglycol sulphate without a rise in 3‐4‐dihydroxyphenylglycol sulphate although free 3‐4‐dihydroxyphenylglycol rises significantly. It is proposed that the latter may be an index of intraneuronal metabolism of noradrenaline and 3‐methoxy‐4‐hydroxyphenylglycol that of released amine.
IN VlTRO BINDING OF PHENYLALANYL‐tRNA TO NEONATAL AND ADULT MOUSE BRAIN RIBOSOMES
Authors: Chou L. , Lerner M. P. , Johnson T. C.
Published: October 2006

Abstract—

The ability of brain ribosomes, isolated from mice of various ages, to bind phenylalanyl‐tRNA was measured under various reaction conditions. In the presence of template RNA (polyuridylic acid) the binding could be measured by both enzymic and non‐enzymic assays. In general, the binding requirements for the brain system were similar to those previously described for microbial and eukaryotic systems. Although previous studies have shown that ribosomes obtained from increasingly older mow brain tissue were less active in polyphenylalanine synthesis, no significant differences in phenylalanyl‐tRNA binding to polysome complexes could be detected. The binding of phenylalanyl‐tRNA by ribosomes isolated from both neonatal and mature mouse brain tissue was similar with regard to GTP and polyuridylic acid dependence, magnesium ion concentration and reaction kinetics. Similar binding of phenylalanyl‐tRNA by young and mature brain ribosomes was also measured with ribonucleoprotein particles previously stripped with puromycin. The results are discussed in light of the rapid alteration of macromolecular synthesis during postnatal brain development and the possible role of the interaction between ribosomes and tRNA.
AMINO ACID METABOLISM AND AMMONIA FORMATION IN BRAIN SLICES
Authors: Weil‐Malherbe H. , Gordon J.
Published: October 2006

The formation of ammonia and changes in the contents of free amino acids have been investigated in slices of guinea pig cerebral cortex incubated under the following conditions: (1) aerobically in glucose‐free saline; (2) aerobically in glucose‐free saline containing 10 mM‐bromofuroic acid, an inhibitor of glutamate dehydrogenase (EC 1.4.1.2); (3) aerobically in saline containing 11‐1 mM‐glucose and (4) anaerobically in glucose‐free saline. Ammonia was formed at a steady rate aerobically in glucose‐free medium. The formation of ammonia was largely suppressed in the absence of oxygen or in the presence of glucose whereas the inhibitor of glutamate dehydrogenase produced about 50 per cent inhibition. Other inhibitors of glutamate dehydrogenase exerted a similar effect. Ammonia formation was also inhibited by some inhibitors of aminotransferases but not by others. Inhibition was generally more pronounced during the second and third hour of incubation.

With the exception of glutamine which decreased slightly, the contents of all amino acids increased markedly during the anaerobic incubation. During aerobic incubation in a glucose‐free medium, there was an almost complete disappearance of glutamic acid and GABA. Glutamine also decreased, but to a relatively smaller extent. The content of all other amino acids increased during aerobic incubation in glucose‐free medium, although to a lesser extent than under anaerobic conditions. The greater increase of amino acids appearing anaerobically in comparison to the increase or decrease occurring under aerobic conditions corresponded closely to the greater amount of ammonia formed aerobically over that formed anaerobically. This finding is interpreted as indicating a similar degree of proteolysis under anaerobic and aerobic conditions; aerobically, the amino acids are partly metabolized with the concomitant liberation of ammonia.

In glucose‐supplemented medium, the content of glutamine was markedly increased. The content of glutamate and aspartate remained unchanged, whereas that of some other amino acids increased but to a lesser extent than in the absence of glucose. Proteolysis in the presence of glucose was estimated at about 65 per cent of that in its absence. In the presence of bromofuroate the rate of disappearance of glutamate was unchanged, but there was a larger increase in the content of aspartate and a smaller decrease of GABA and glutamine. Other changes did not differ significantly from those observed in the absence of bromofuroate. We conclude that the metabolism of amino acids in general and of glutamic acid in particular differs according to whether they are already present within the brain slice or are added to the incubation medium. Only the endogenous amino acids appear to be able to serve as precursors of ammonia and as substrates for energy production.
THE DETERMINATION OF ACETYLCHOLINESTERASE ACTIVITY OF BRAIN SLICES AND ITS SIGNIFICANCE IN STUDIES OF EXTRACELLULAR ACETYLCHOLINESTERASE
Authors: Hobbiger F. , Lancaster R.
Published: October 2006

The AChE activity of single slices obtained from the surface of the temporoparietal region of rat brains was measured colorimetrically under anaerobic conditions with acetylthiocholine as substrate. In intact slices from untreated rats AChE activity was only a small proportion of that of homogenates made from the slices, but this proportion increased with the surface area to weight ratio of slices and with an increase in substrate concentration, intact slices not showing substrate inhibition. The inhibition of AChE determined in slices from rats treated with DFP or paraoxon was less than that in homogenates obtained from the slices. When the access of substrate was limited to the cut surface of a slice, the rate of hydrolysis was four times greater than that observed when access was solely from the uncut surface. It is concluded that under anaerobic conditions the substrate diffuses into slices to a depth which is not constant but a function of both substrate and enzyme concentration. Thus the AChE activity of slices cannot be used as a measure of extracellular AChE.
QUAKING MOUSE: ISOLATION AND CHARACTERIZATION OF MYELIN PROTEIN
Authors: Greenfield S. , Norton W. T. , Morell P.
Published: October 2006

A new technique, involving final purification on a continuous CsCl gradient, was utilized for the isolation of cerebral myelin from adult (4‐ to 6‐month‐old) quaking mice, littermate controls and young (10‐day‐old) normal mice. The yield of myelin from either adult quaking or normal young mice was 5‐10 per cent of that from adult controls. After deli‐pidation, myelin proteins were separated by polyacrylamide gel electrophoresis in buffers containing sodium dodecylsulphate. Two gel systems were utilized: (1) a high‐resolution discontinuous electrophoresis system; and (2) a continuous system utilizing gels cross linked with ethylenediacrylate (EDA). The gels from the discontinuous system were stained with Fast Green and quantified by densitometry. The base lability of the EDA‐linked gels permitted direct chemical determination of protein in specific bands.

Myelin from brains of normal adult mice contained, as major components, one proteo‐lipid and two basic proteins. There were also a number of high‐molecular‐weight proteins which represented a significant portion of the total. Myelin from quaking mice had qualitatively a similar distribution of proteins but the high‐molecular‐weight fraction comprised a much greater percentage of the total protein. The ratio of basic to proteolipid protein in preparations from quaking mice was considerably higher than that in the myelin from control mice. The distribution pattern of the myelin proteins from 10‐day‐old mice was quantitatively similar to that of quaking mice. Altogether the evidence supports the hypothesis that the quaking mutant provides a model of an immature nervous system with respect to myelination.