bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARISON OF THE FATTY ACIDS OF LIPIDS OF SUBCELLULAR BRAIN FRACTIONS
Authors: Kishimoto Y. , Agranoff B. W. , Radin N. S. , Burton R. M.
Published: October 2006

Abstract— Rat brain grey and white matter were fractionated to yield myelin, nerve terminal, synaptic vesicle, nerve terminal ‘ghost’, and microsomal fractions of white and grey matter. Ester‐type glycolipids were found in all fractions except myelin, while cerebrosides occurred in significant concentrations only in myelin and white microsomes. Comparison of the fatty acid profile of the ethanolamine‐ and serine‐containing phospholipids showed marked differences between myelin and the particles from grey matter, while the microsomes of white matter were of intermediate composition. Docosahexaenoic acid, a minor acid in myelin, was a major fatty acid in microsomes of grey and white matter. The fatty acid composition of sphingomyelin was distinctly different in the fractions derived from grey and white matter, clustering about stearate and nervonate in the latter, but only about stearate in the grey. Marked differences in the positional distribution of fatty acids were seen within phosphatidyl choline from myelin and nerve terminals. Ribonucleic acid was found in nerve terminal and synaptic vesicle fractions. The sphingosine found in the ganglioside from microsomes of both grey and white matter was similar with respect to distribution of the C18 and C20 homologues.

The possibility is discussed that microsomes furnish characteristic lipids for the synthesis or renewal of specific membranes, and that these lipids are accumulated somewhat before being released.
BINDING OF d‐[DIMETHYL14C]TUBOCURARINE, ACETYLCHOLINESTERASE AND PROTEOLIPIDS IN SUBCELLULAR MEMBRANES OF CEREBRAL CORTEX OF THE DEVELOPING RAT1
Authors: Gömez C. J , Pasquini Juana M , Soto E. F , Robertis E. De
Published: October 2006

Abstract— The cerebral cortex of rats at postnatal ages of 5,15,30 and 50 days was homogenized and fractionated to separate the crude mitochondrial fraction. This fraction was osmotically shocked and the Mi fraction and subfractions were separated. The variations with age in the morphological composition of subfractions M1 0·8, Mi 1·3 and M1p were studied under the electron microscope. Because of the changes observed in the various fractions the need for such type of control is stressed.

The changes in total protein and proteolipid‐protein of the fractions at different ages, as well as the acetylcholinesterase activity and the binding of d‐[dimethyl−14C]tubocurarine were studied. The results obtained were interpreted on the basis of the important morphogenetic changes that the cerebral cortex undergoes postnatally. The progressive and parallel increase in acetylcholinesterase and in the binding of d‐[dimethyl‐14C]tubocurarine to proteolipids of fraction Mi 1·3, suggest a close relationship between these two events and the development of the cholinergic synapses.
A LIGHT‐SCATTERING TECHNIQUE FOR THE STUDY OF THE PERMEABILITY OF RAT BRAIN SYNAPTOSOMES IN VITRO
Authors: Keen P , White T. D
Published: October 2006

Abstract— (1) Swelling of synaptosomes was measured spectrophotometrically by recording changes in extinction at 520 nm.

(2) Synaptosomes behaved as osmometers in NaCl solutions. When the tonicity of the medium was changed, synaptosome volume changed in accordance with Boyle and van't Hoff's Law. These changes were reversed on restoring the tonicity of the medium.

(3) The rate at which a solute entered the synaptosome was determined from the rate of swelling in the presence of that solute. Permeability of synaptosomes to non‐electrolytes was in the order glucose ≪ glycerol < thiourea = formamide < propylene glycol = dimethylsulphoxide.

(4) Synaptosomes were freely permeable to ammonium and acetate ions and impermeable to Ca2+, Mg2+, PO42−, SO42− and oxalate ions.
CHANGES WITH AGE IN WATER AND EXTRA‐CELLULAR SPACE IN INCUBATED BRAIN TISSUE
Authors: Levi G , Lattes Maria G
Published: October 2006

Abstract— (1) Incubation in physiological saline at 37º caused brain slices from chick embryos to lose water (shrink), whereas slices from young chicks gained water (swell). Shrinkage decreased with age in embryonic brain, and swelling increased with age in chick's brain.

(2) Incubation at 0º diminished shrinkage in 8‐day old embryos, caused an increasing degree of swelling in older embryos, and enhanced swelling in young chick's brain slices.

(3) Inulin equilibrated more rapidly with tissue water in embryonic than in young adult brains. Measured ‘inulin space’ values at 37º changed little with age, whereas 0º‘inulin space’ values significantly decreased with age. Calculated zero time ‘inulin space’ values also decreased with age.

(4) The measured ‘inulin space’ at 0º was larger than that measured at 37º (but not of the calculated zero time ‘inulin space’) in young embryos, then became progressively smaller, so that in young chicks the situation was reversed.

(5) The calculated extracellular space ranges from about 37 per cent (8‐day old embryos) to about 14 per cent (15‐day old chicks).

(6) Incubation in the absence of glucose had more effect on brain slices from young chicks than from embryos. The opposite was true when a hypotonic medium or a medium containing d‐glutamate was used.
EFFECTS OF SHOCK AND ANOXIA ON NUCLEOTIDES AND CREATINE PHOSPHATE IN THE ISOLATED BRAIN OF THE DOG1
Authors: Minsker D. H. , Gilboe D. D. , Stone W. E.
Published: October 2006

Surgically isolated canine brains were maintained with compatible donor blood from an extracorporeal perfusion system. Small samples of frozen cerebral cortex were removed with a newly‐developed Freon cryoprobe and were analysed for acid‐soluble nucleotides, creatine phosphate and inorganic phosphate. Most animals were in the early stages of shock unless they had received preoperative α‐adrenergic blockade with phenoxybenzamine hydrochloride (Dibenzyline). Values for high‐energy phosphates were in the normal range only when the animal had been premedicated with phenoxybenzamine hydrochloride. During a 4‐min period of anoxia (induced by blood which had been equilibrated with 95% N2 and 5% CO2), the cerebral cortex rapidly became iso‐electric, and the levels of creatine phosphate and ATP decreased concomitantly with increases in levels of ADP and Pi. These electrical and chemical changes were rapidly and completely reversed by reoxygenation. The levels of high‐energy phosphates provide a sensitive criterion of functional adequacy that may be more readily quantitated than cerebral electrical activity (EEG). EEG recovery did not correlate closely with rephosphorylation.
EFFECTS OF DOPAMINE, GAMMA‐AMINOBUTYRIC ACID AND 5‐HYDROXYTRYPTAMINE ON INCORPORATION OF 32P INTO PHOSPHATIDES IN SLICES FROM THE GUINEA PIG BRAIN1
Authors: Hokin Mabel R.
Published: October 2006

(1) Dopamine–In slices from guinea pig corpus striatum, dopamine significantly inhibited incorporation of 32P into phosphatidylethanolamine‐plus‐phosphatidylserine at a concentration of 0001 mM, and into phosphatidylinositol and phosphatidylcholine at 001 mM. In eight areas of the guinea pig brain in which the effects of 01 mM‐dopamine were studied, the only significant increase in incorporation of 32P into phosphatides was into phosphatidic acid in the hypothalamus; there was significant inhibition of incorporation of 32P into phosphatidylcholine in cerebellar cortex and thalamus, and into phosphatidylethanolamine‐plus‐phosphatidylserine in the olfactory bulbs.

(2) Gamma‐aminobutyric acid—In slices of guinea pig cerebral cortex, GABA (1 mM) significantly inhibited incorporation of 32P into only phosphatidic acid, diphosphoinositide and phosphatidylinositol and did not significantly affect the level or the specific activity of the nucleotide ∼P. GABA (10 mM), significantly inhibited incorporation of 32P into diphosphoinositide, phosphatidylinositol and phosphatidylcholine, and significantly lowered the specific activity of the nucleotide ∼P.

(3) 5‐Hydroxytryptamine—In slices of guinea pig cerebral cortex, 5HT, (1 mM) significantly increased incorporation of 32P into phosphatidic acid; in a concentration of 10 mM, 5HT increased incorporation of 32P into phosphatidic acid four‐fold and into both diphosphoinositide and phosphatidylinositol two‐fold; other phosphatides were not significantly affected and the specific activity of the nucleotide ∼P was not significantly different. In eight brain areas studied, 5HT (10 mM) significantly increased incorporation of 32P into phosphatidic acid in all areas; into phosphatidylinositol in six areas (excepting cerebellar cortex and hypothalamus); and into diphosphoinositide in the olfactory bulbs, cerebral cortex, hypothalamus and corpus striatum. Incorporation of 32P into triphosphoinositide was not significantly affected in any area. Incorporation of 32P into phospha‐tidylethanolamine‐plus‐phosphatidylserine was significantly greater than the control in the olfactory bulbs and incorporation of 32P into phosphatidylcholine was significantly less than the control in the cerebellar cortex, olfactory bulbs and hypothalamus.

(4) The possibility is discussed that increased incorporation of 32P into phosphatidic acid and/or phosphatidylinositol in response to neurotransmitters might be associated with excitatory, but not inhibitory, neurotransmission; and that inhibition of incorporation of 32P into various phosphatides may be associated with inhibitory neurotransmission or neuromodulation.
THE EFFECT OF METHIONINE SULPHOXIMINE ON THE INCORPORATION OF LABELLED GLUCOSE, ACETATE, PHENYLALANINE AND PROLINE INTO GLUTAMATE AND RELATED AMINO ACIDS IN THE BRAINS OF MICE
Authors: Van den Berg C. J. , Van den Velden J.
Published: October 2006

—The incorporation of radioactivity from labelled glucose, acetate, phenylalanine and proline into glutamate, aspartate and glutamine was measured in mice treated with methionine sulphoximine and in the control animals. The labelled precursors were injected and their incorporation determined before the onset of convulsions. The incorporation of radioactivity from labelled glucose into the dicarboxylic amino acids was reduced, in particular the incorporation into glutamine. The incorporation of radioactivity from labelled acetate and phenylalanine into glutamate and aspartate was increased by methionine sulphoximine, while the incorporation into glutamine was not changed very much. The labelling of glutamine, relative to glutamate, was reduced with all precursors, indicating that glutamine synthetase was inhibited in vivo by methionine sulphoximine. It is very likely that methionine sulphoximine affects many aspects of energy metabolism in brain; in particular the metabolism of glucose seems to be inhibited, while the rate of conversion of substrates other than glucose seems to be increased.
THE EFFECT OF METHIONINE ON THE REGIONAL AND INTRACELLULAR DISPOSITION OF [3H]‐METHIONINE SULPHOXIMINE IN RAT BRAIN1
Authors: Ghittoni Nora E. , Ohlsson W. G. , Sellinger O. Z.
Published: October 2006

—The intracellular disposition of the convulsant agent, methionine sulphoximine (MSO), administered as methyl‐labelled [3H]MSO, was examined in rat brain. Intraperitoneal (i.p.) and intrathecal (i.th.) routes were compared. The effect of simultaneous administration of methionine on the uptake, the regional distribution and the intracellular disposition of [3H]MSO was also assessed:

(1) The peak uptake of i.p. [3H]MSO was at 2 h and amounted to about 1 per cent of the dose; the peak uptake of i.th. [3H]MSO was at 30 min post‐injection and amounted to 40 per cent of the administered dose. The uptake was effectively reduced when methionine was simultaneously administered.

(2) The regional distribution of [3H]MSO as a function of time after injection revealed a rather uniform penetration of the entire brain by the drug. A maximum of 43 per cent of the tissue radioactivity was found in the cerebellum 2 h after i.p. injection, while 49 per cent accumulated in the extracortical portion of the brain 3·5 h after i.th. administration. Methionine did not affect the regional distribution of [3H]MSO.

(3) Differential centrifugation of samples of cortex and cerebellum revealed an association of [3H]MSO with intracellular particulate fractions. Since closely similar proportions of MSO occurred in the crude mitochondrial and the microsomal fractions, these fractions were analysed further: (a) [3H]MSO was bound to nerve endings sedimenting at the 1·0 m–1·2 m‐sucrose interface; this binding was not abolished by prior increase of the endogenous cerebral methionine pool; and (b) [3H]MSO was released by subjecting the nerve endings to osmotic shock. However, the striking finding was that [3H]MSO could not be released from the nerve endings of the cerebellum from animals pre‐treated with methionine.

(4) An association of [3H]MSO was observed with the membranes of the endoplasmic reticulum and specifically with its agranular component.

(5)The results implicate the cerebellum as the primary target for MSO, in confirmation of the original observations of Lodin (1958).
AMINO ACID INCORPORATION IN VITRO INTO PROTEIN OF NEURONAL AND GLIAL CELL‐ENRICHED FRACTIONS
Authors: Blomstrand C. , Hamberger A.
Published: October 2006

Abstract—

Slices of rabbit cerebral cortex were incubated in the presence of labelled amino acids. Following incubation, neuron‐ and gliaenriched fractions were obtained by density gradient centrifugation and the TCA‐insoluble radioactivity determined. The protein‐bound radioactivity was five to six times higher in the neuronal‐enriched fraction than in the glial‐enriched fraction after incubation with tritiated leucine. The neuronal fraction incorporated also a number of other amino acids to a higher extent than the glial fraction (neuron/glia ratio 2·5‐6). A definite dependence of incorporation on the rate of oxygenation was demonstrated. The suppression of amino acid incorporation was more marked for the neuronal fraction than for the glial fraction during incubation in relative hypoxia. An increase of potassium concentration in the incubation medium enhanced the amino acid incorporation in both fractions. Low sodium levels decreased the incorporation. Puromycin inhibited incorporation to approximately 30 per cent of control for both fractions. Addition of cycloheximide and dinitrophenol resulted in greater inhibition of incorporation in the neuronal fraction than in the neuroglial fraction. Actinomycin D did not markedly affect the incorporation in any fraction. These results are discussed in relation to in vivo and in in vitro differences for transport and incorporation of amino acids.
HYDRAZIDE‐INDUCED SEIZURES AND CEREBRAL OF LEVELS γ‐AMINOBUTYRIC ACID: A RE‐EVALUATION
Authors: Abrahams Dawne E. , Wood J. D.
Published: October 2006

Abstract—

Data have been presented indicating that in chicks the time lag in the onset of seizures after the administration of hydrazides was not caused by a slow penetration of the convulsant agents into the brain. A correlation was evident between the rate of decrease in concentration of cerebral GABA and the susceptibility of chicks to hydrazide‐induced seizures. Earlier studies precluding a role for GABA in hydrazide‐induced convulsions were re‐examined.
GLUTAMATE AND RELATED AMINO ACIDS IN CAT SPINAL ROOTS, DORSAL ROOT GANGLIA AND PERIPHERAL NERVES
Authors: Duggan A. W. , Johnston G. A. R.
Published: October 2006

Abstract—

Of the free amino acids found in extracts of cat spinal roots, dorsal root ganglia and peripheral nerves, only glutamate was present in disproportionately high concentrations in those parts of the dorsal roots between ganglia and spinal cord. This distribution suggests that the high dorsal root levels of glutamate may result from synthesis in dorsal root ganglia and subsequent transport towards the spinal cord. Four excitant amino acids were detected in the extracts: aspartate, cysteate, cysteine sulphinate and glutamate. The unique regional distribution of glutamate is consistent with the proposed role of this amino acid as an excitatory transmitter at the terminals of primary afferent fibres.
LOCALIZATION OF TYROSINE TRANSAMINASE IN RAT BRAIN
Authors: Mark J. , Pugge H. , Mandel P.
Published: October 2006

Abstract—

The distribution of rat brain tyrosine transaminase was determined in brain regions and in subcellular fractions. The results indicate that brain tyrosine transaminase is predominantly a mitochondrial enzyme. Its localization on the inner mitochondrial membrane is suggested. The results are discussed in relation to the function of tyrosine as precursor of catecholamines in the central nervous system.
ENHANCEMENT OF BRAIN THIAMINE DIPHOSPHATASE ACTIVITY OF RATS BY INJECTION OF CHOLINERGIC DRUGS
Authors: Iwata H. , Inoue A. , Tomoi M.
Published: October 2006

Abstract— The effects of cholinergic drugs on thiamine diphosphatase (TDPase) in rat brain, liver and kidney were studied to clarify the role of the enzyme in the central nervous system.

Brain TDPase activity was markedly increased by intraperitoneal injection of a sub‐lethal dose of physostigmine, ambenonium or pentetrazol. These drugs also increased the activity in the kidney, but not liver. Strychnine, atropine, and scopolamine did not affect the activity of brain TDPase, but decreased the enzyme activity of liver and kidney. Physostigmine also increased the activity of brain thiamine monophosphatase.

Brain TDPase activity reacheda maximum 30 minafterphysostigmine injection (1.0mg/kg). However, inhibition of brain acetylcholinesterase activity was greatest 45 min after physostigmine injection. The TDPase and AChE activities had both returned to normal values 60 min after the injection. The durations of these changes of TDPase and AChE activity corresponded to the duration of the tremor induced by physostigmine. The contents of total and phosphorylated thiamines in the brain but not in the liver or kidney were significantly reduced by physostigmine.

The relationship between ACh and activation of TDPase activity by cholinesterase inhibitors is discussed.
DISTRIBUTION OF POLYSOMES IN MOUSE BRAIN TISSUE
Authors: Lerner M. P. , Wettstein F. O. , Herschman H. R. , Stevens J. G. , Fridlender B. R.
Published: October 2006

Abstract— Polysomes were isolated from several different fractions of mouse brain tissue. After homogenization, the extract was centrifuged to yield a post‐mitochondrial supernatant fraction and a pellet fraction. Sucrose gradient analysis of the material in the post‐mitochondrial supernatant fraction indicated that 80 per cent of the ribosomes were present in polysomes and that little, if any, of the pellet fraction was present. Sucrose gradient analysis of the solution obtained after washing the pellet showed that very little polysomal material was present. The remaining pellet fraction was resuspended in a detergent mixture of deoxycholate‐Tween 40. Sucrose gradient analysis of the resulting detergent‐soluble solution indicated that large amounts of ribosomal material, in which 60–70 per cent of the ribosomes were associated in polysomes, were present.

In brain tissue from young animals, 20 per cent of the polysomes were found in the post‐mitochondrial supernatant fraction whereas 80 per cent of the polysomes were released from the pellet fraction by detergent treatment. In contrast, in brain tissue from adult animals, 40 per cent of the polysomes were found in the post‐mitochondrial supernatant fraction, whereas 60 per cent of the polysomes were released from the pellet fraction by detergent treatment.
SUBCELLULAR FRACTIONATION OF GANGLIOSIDE SIALIDASE FROM HUMAN BRAIN
Authors: ÖHman R.
Published: October 2006

—A subcellular fractionation was performed on forebrain cortex from three human brains and the fractions obtained were assayed for ganglioside sialidase and four p‐nitrophenyl glycohydrolases. Differences in the sedimentation patterns of the enzymes were observed. From 53 to 77 per cent of the recovered sialidase activity was found in the synaptosomal fraction, while the p‐nitrophenyl glycosidases were mainly recovered in the lysosome‐enriched fraction. Three possible interpretations of the sialidase sedimentation pattern are suggested: (1) The ganglioside sialidase is bound to the limiting membrane structure of the nerve ending. (2) The ganglioside sialidase is lysosomal, although bound to lysosomes of low density. (3) The enzyme occurs mainly in lysosomes primarily located in the nerve endings, being trapped under the formation of the synaptosomes.
PROTEIN SYNTHESIS IN VITRO IN RAT BRAIN AFTER SHORT‐TERM PROTEIN STARVATION AND REFEEDING
Authors: Von der Decken Alexandra , Wronski A.
Published: October 2006

Abstract—

Rats were fed a protein‐free diet for 4 or 6 days. They were compared with rats kept on the same diet for 3 or 5 days and on adequate protein for one additional day. The incorporation of 14C‐labelled amino acid into protein was studied in systems containing ATP, GTP, phosphoenolpyruvate, pyruvate kinase and if required, a mixture of unlabelled amino acids and either the 6000 g supernatant fraction of a brain homogenate or microsomes and soluble enzymes. The 6000 g supernatant fraction showed variation in amino acid incorporating activity as well as in RNase activity as measured by breakdown of labelled polyuridylic acid. There was no difference in RNase activity in isolated microsomes, but the amino acid incorporating activity was significantly higher in preparations obtained from rats fed one meal of protein after 5 days of protein‐starvation.
MULTIPLE FORMS OF MONOAMINE OXIDASE IN DEVELOPING BRAIN: TISSUE AND SUBSTRATE SPECIFICITIES
Authors: Shih Jean‐Hung C. , Eiduson S.
Published: October 2006

Brains, 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

The 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.
CONTENT AND TURNOVER OF GANGLIOSIDES IN RAT BRAIN FOLLOWING BEHAVIOURAL STIMULATION1
Authors: Irwin L. N , Samson F. E
Published: October 2006

Abstract— Rats were placed in a tank of deep water to swim until they learned to escape (Group E) or were lifted out (Group F). Controls (Group C) were left in their home cages. Specific radioactivities of purified gangliosides, other glycolipids and nonlipid carbohydrates were measured at 9 and 24 h after intracranial injection of D‐[1‐14C]glucosamine and the subsequent swimming trials. Nonspecific effects of behavioural stimulation (similar changes in Groups E and F) included decreased net incorporation of radioactivity into monosialogangliosides and nonganglioside carbohydrates, a relative increase in content of GT1 gangliosides and decreased content of GT1 gangliosides. Specific effects (different changes in Groupe E and F) included in Group E decreased net uptake of radioactivity into disialogangliosides. These results demonstrate that in rat brain: (1) ganglioside metabolism is affected by behavioural stimulation; (2) metabolism of other heteropolysaccharides is also affected; and (3) some biochemical changes are consequences of nonspecific stimulation whereas others are associated with specific elements of experience.
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

Incorporation 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

The 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.
OXIDATIVE PHOSPHORYLATION BY PYRIDOXINEDEFICIENT RAT BRAIN MITOCHONDRIA1,2
Authors: Bhuvaneswaran C. , Dakshinamurti K.
Published: October 2006

Abstract— Oxygen uptake, ADP/O ratios and respiratory control ratios (RCR) were studied by the oxygen electrode technique in mitochondria prepared from adult and neonatal brains from normal and pyridoxine‐deficient rats. The mitochondria from neonatal brain exhibited decreased rates of substrate oxidation, ADP/O ratios and respiratory control ratios in comparison to those obtained with mitochondria from the respective adult brains. The cytochrome contents of the neonatal brains were also less than those of the adults. Within the neonatal or adult groups, there were no differences in any of the parameters tested between the normal and pyridoxine‐deficient rats.
CATECHOLAMINE INDUCED INCREASE OF CYCLIC ADENOSINE 3′,5′‐MONOPHOSPHATE IN RAT BRAIN IN VIVO
Authors: Burkard W. P.
Published: October 2006

Abstract— Four catecholamines injected into the cerebral ventricles increased the content of cyclic adenosine 3′,5′‐monophosphate (cAMP) in vivo in the whole brain of rats. The highest rise (2.6‐fold) was measured 2 min after an injection of 100 μg epinephrine. Isoproterenol and norepinephrine were less active and dopamine hardly increased the cAMP level. These results are compatible with the view that physiological actions of catecholamines in the nervous system may be mediated by an increase of CAMP.
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.
FATTY ACID COMPOSITION OF CEREBROSIDES, SULPHATIDES AND CERAMIDES IN MURINE LEUCODYSTROPHY: THE QUAKING MUTANT
Authors: Joseph K. C. , Druse M. J. , Newell L. R. , Hogan E. L.
Published: October 2006

Abstract— The fatty acid composition of cerebrosides, sulphatides and ceramides has been determined at 20 days postpartum in the brains of Quaking mutant mice and of littermate controls. There was a significant deficit in the proportion of long‐chain fatty acids (C22‐C24) affecting both normal and a‐hydroxy fatty acids of the cerebrosides. The proportion of normal but not the a‐hydroxy long‐chain fatty acids of the sulphatides was also decreased. Striking and disproportionate deficits of the C24:1 and C24 h:1 fatty acids of cerebrosides, sulphatides and ceramides characterized the brain of the Quaking mutant, and an increased proportion of C23 h:O fatty acid was found in the cerebrosides and sulphatides of the brain of this mutant. We compared these data with findings on the Jimpy mutant which has been examined by the same techniques. The deficiency of long‐chain fatty acids which was found in the cerebrosides and sulphatides of both mutants was less extensive but more selective in the Quaking mutant.
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.
THE PURIFICATION AND PROPERTIES OF BOVINE PINEALS‐ADENOSYLMETHIONINE:N‐ACETYLSEROTONINO‐METHYL TRANSFERASE
Authors: Karahasanoǧlu A. M. , ÖZand P. T.
Published: October 2006

Abstract—Bovine pineal glandS‐adenosylmethionine:N‐acetylserotoninO‐methyltransferase has been purified about 2800‐fold using cell fractionation, ammonium sulphate treatment, Sephadex G‐200 gel filtration and anion exchange chromatography. The enzyme has been found to be a polymer; the smallest unit observed had a mol. wt. of 21,800 and the other polymers' molecular weights were multiples of this figure. In the gland extract polymers of 83,000, 100,000, 125,000 and 150,000 mol. wt. were more abundant than the others; they showed also higher specific activity. One of the products of the reaction,S‐adenosylhomocysteine was found to be a potent inhibitor, whereas the other product, melatonin, did not inhibit the bovine pineal gland enzyme, even at much higher concentrations. Homocysteic acid, cysteic acid, GSG and GSSG inhibited the enzyme. The required concentrations for this effect was 100 times higher than that ofS‐adenosylhomocysteine. The addition of GSH to the medium during purification led to complete loss of activity. Adenosine, homocysteine and other thio compounds had little or no effect. The enzyme was found to be activated by its substrates and also by certain anions. Among various organic acid salts, citric acid cycle intermediates were found to be good activators; their nonsubstituted analogues were not as effective. The activator effect of oxaloacetate and bicarbonate was the highest, and was brought about by relatively low concentrations of these anions (1–5 × 10−3M), hence their effect was considered specific. The degree of activation caused by oxaloacetate was decreased by increasing substrate concentrations and vice versa. TheS‐adenosylhomocysteine inhibition could not be reduced by increasing the substrate concentration;S‐adenosylhomocysteine also inhibited the oxaloacetate‐activated enzyme. These observations have been explained by the allosteric behaviour of the enzyme. The kinetic behaviour of various polymers was also investigated. The highest substrate and oxaloacetate activation and the highestS‐adenosylhomocysteine inhibition was observed for polymers of 83,000, 100,000, 125,000 and 150,000 mol. wt. The Kmvalues forS‐adenosylmethionine andN‐acetylserotonin calculated for the oxaloacetate activated enzyme were also lower for these polymers than others.
IMPAIRED MYELIN FORMATION IN EXPERIMENTAL HYPERPHENY LALANINAEMIA1
Authors: Shah S. N. , Peterson N. A. , McKean C. M.
Published: October 2006

Abstract— From the 5th to the 20th postnatal day, rats were injected with saline (controls) or phenylalanine (3 mg/g daily). The quantities of cholesterol and glycolipids were significantly lower in the phenylalanine‐injected rats, but brain DNA and protein contents were the same in both groups. As a result of the reduced formation of lipids, the hyperphenylalaninaemic brains contained significantly less myelin than control brains, but the gross composition [ratio of protein: cholesterol: galactolipid: phospholipid) of the myelin was unchanged. We suggest that in hyperphenylalaninaemic brains the reduced availability of cholesterol may cause a reduction in the formation of cholesterol‐phospholipid‐protein complexes in brain, which in turn may limit the formation of myelin.
PROTEOLYTIC ACTIVITY AND BASIC PROTEIN LOSS IN AND AROUND MULTIPLE SCLEROSIS PLAQUES: COMBINED BIOCHEMICAL AND EIISTOCHEMICAL OBSERVATIONS
Authors: Einstein E. R. , Csejtey J. , Dalal K. B. , Adams C. W. M. , Bayliss O. B. , Hallpike J. F.
Published: October 2006

Abstract— This combined histochemical and biochemical study has shown that acid proteinase activity (PH 3.5) is increased around histologically‐defined active plaques of multiple sclerosis (MS). Biochemical estimation showed that the enzyme is more active in most samples of ‘normal’ white matter in MS than in controls. A gradient of enzyme activity was observed: control white matter‐white matter distant from plaqueclose white matter‐edgsplaque. Both electrophoretic and histochemical techniques revealed a reduction or absence of basic (encephalitogenic) protein in the plaques. Electrophoresis showed a diminution of encephalitogenic protein outside some plaques. Phospholipids that remain on the base‐line of thin‐layer chromatoplates were shown to be predominantly phosphoinositides combined with encephalitogenic protein
THE RELATIONSHIP BETWEEN AMINO ACID INCORPORATION INTO PROTEIN IN ISOLATED NEOCORTEX SLICES AND THE TISSUE CONTENT OF FREE AMINO ACID
Authors: Jones D. A.
Published: October 2006

Abstract— The uptake of radioactive leucine by incubated neocortex slices was found to be increased by electrical stimulation, yielding a higher content of radioactive amino acid per g fresh weight of tissue which was maintained for prolonged periods of stimulation. The increased tissue content may be associated with tissue swelling found on electrical stimulation, but the additional amino acid uptake was by an active process rather than by passive diffusion. Additions of valine (2.5–10 mm) or tryptophan (1 mm) to the incubation medium was found to depress the tissue leucine content. Decreasing the tissue free leucine content by incubating slices in medium containing 5 mm‐valine was found to decrease the incorporation of leucine and lysine into tissue protein, indicating that under these conditions tissue free amino acid becomes rate limiting for amino acid incorporation into protein. By analogy with the properties of cerebral tissue in oitro it is suggested that electrical activity in vivo may cause localized increases in free amino acid concentration which may serve to regulate protein synthesis in conditions where the concentration of free amino acids are rate limiting.
Brain serotonin and norepinephrine after convulsions and reserpine1
Authors: Feighner J. P. , Lao L. , King Lucy J. , Ross W. J.
Published: October 2006

Decreased brain norepinephrine (Schildkraut, 1969) and decreased brain serotonin (Shaw, Camp and Eccleston, 1967; Bourne et al., 1968) have been implicated in current hypotheses about the psychiatric syndrome, depression. Reserpine, which causes depression in some people, depletes brain norepinephrine and serotonin and, possibly, replicates in laboratory animals some of the biochemical changes in brains of depressed patients. Electrically‐induced convulsions are an effective treatment of depression. There have been numerous studies of the effects of convulsive electrical stimulation on norepinephrine and serotonin in brains of laboratory animals. They have employed different schedules of administration of convulsions, short (minutes) or long (hours to days) periods after convulsion before killing the animals, and various methods of extraction and assay of the amines. Results have varied. For example, Kato, Gozsy, Roy and Groh (1967) found that a series of convulsions, administered daily for 11 days elevated whole brain serotonin but not norepinephrine. On the other hand, Hinesley, Norton and Aprison (1968) observed that a series of seven convulsions, one every other day, elevated norepinephrine only in cerebral hemispheres, whereas serotonin was elevated only in midbrain and pons‐medulla. Our present report is the first to deal with both norepinephrine and serotonin in animals given both serial injections of reserpine and a series of electrically‐induced convulsions.
TRANSPORT OF l‐TRYPTOPHAN INTO SLICES OF RAT CEREBRAL CORTEX1
Authors: Kiely Maureen , Sourkes T. L.
Published: October 2006

—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

—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

—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.
INTERRELATIONSHIPS BETWEEN POLYAMINES AND NUCLEIC ACIDS. CHANGES OF POLYAMINE AND NUCLEIC ACID CONCENTRATIONS IN THE GROWING FISH BRAIN (SALMO IRIDEUS GIBB.)
Authors: Seiler N. , Lamberty Ursula
Published: October 2006

Abstract— In contrast to mouse brain, the content of putrescine in fish brain considerably exceeds that of spermine and spermidine. While we observed constant protein, RNA and spermidine concentrations in fish brains of weights between 60 and 800 mg, DNA and spermine concentrations diminished with increasing brain weight, the content of spermine per cell being constant throughout life. It can be concluded from our results that growth of fish brain results both from cell enlargement and cell proliferation. The concomitant changes of spermine and DNA concentrations in the growing fish brain are the first example of a direct quantitative relationship between these cell constituents and provides evidence on their possible functional relationship in the cell nucleus.
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.