bluuebunny/crossref_metadata_2025 huggingface dataset:
POLYRIBOSOME DISAGGREGATION AND CELL‐FREE PROTEIN SYNTHESIS IN PREPARATIONS FROM CEREBRAL CORTEX OF HYPERPHENYLALANINEMIC RATS1
Authors: Siegel F. L. , Aoki K. , Colwell R. E.
Published: December 2006

Abstract— Seven‐day‐old rats were injected intraperitoneally with l‐phenylalanine (1 g/kg) and the time course of brain polyribosome disaggregation and changes in brain levels of phenylalanine, tryptophan and tyrosine were determined. Disaggregation of brain polyribosomes preceded the increase in levels of phenylalanine in brain, and followed the same time course as depletion of tryptophan from brain.

The effects of several metabolites of phenylalanine (which are formed in phenylketonuria) on protein synthesis in vitro was determined for brain and liver systems. None of the compounds tested was inhibitory at concentrations below 10 mM and in all cases hepatic protein synthesis was more sensitive to inhibition than was the corresponding system from brain.

Ribosomal dimers, formed in brain after injection of phenylalanine, were incapable of supporting high levels of protein synthesis in vitro, a finding that suggested that the inhibition of protein synthesis in vitro in cell‐free systems of brain tissue after injection of phenylalanine into young rats was mediated by disaggregation of brain polyribosomes associated with tryptophan deficiency in brain.
EVIDENCE FOR SEPARATE SYSTEMS FOR THE TRANSPORT OF NEUTRAL AND BASIC AMINO ACIDS ACROSS THE BLOOD‐BRAIN BARRIER
Authors: Richter J. J. , Wainer A.
Published: December 2006

Abstract— The effects of high circulating concentrations of several amino acids on the free amino acids of rat brain were measured, to see whether or not the results followed any consistent pattern. High circulating concentrations of large, neutral amino acids (phenylalanine, valine or isoleucine) caused significantly decreased values only of other large, neutral amino acids in the brains. High circulating concentrations of the basic amino acids lysine or arginine caused significantly decreased values only of each other. The data suggest that there are separate systems for the transport of neutral and basic amino acids across the blood‐brain barrier. The effects of valine and lysine on the uptake by brain and the con‐vulsant action of allylglycine (a neutral amino acid) were consistent with the concept of separate systems for the transport of amino acids across the blood‐brain barrier. Valine inhibited the uptake by brain and the convulsant action of allylglycine in mice, but lysine did not. The data suggest that allylglycine and valine are transported into the brain by a common mechanism that does not transport lysine.
APPEARANCE OF A BRAIN‐SPECIFIC ANTIGEN (S‐100 PROTEIN) IN THE DEVELOPING RAT BRAIN1
Authors: Herschman H. R. , Levine L. , De Vellis J.
Published: December 2006

Abstract— Thelevel of the S‐100 protein, a brain‐specific antigen, wasdetermined by quantitative complement fixation in the brain stem and cerebrum of the rat during postnatal maturation. The content was minimal at birth in the brain stem and rose to its adult value by day 25. Although S‐100 protein could not be detected in the cerebrum of the 2‐day‐old rat, adult values were also present by the 25th day of age. Neither single dose X‐irradiation with 750 rd to the head at 2 days of age or single dose X‐irradiation at 11 days of age affected the adult level of S‐100 protein in the brain stem or cerebrum. Similarly, hypophysectomy at 20 days of age had no effect on the subsequent levels of S‐100 protein.
FATTY ACIDS AND LONG CHAIN BASES OF VERTEBRATE BRAIN GANGLIOSIDES
Authors: Avrova N. F. , Zabelinskiï S. A.
Published: December 2006

Abstract— Fatty acid and long‐chain base composition of gangliosides from brains of animals belonging to various vertebrate classes (fishes, amphibia, reptiles, birds and mammals) was studied by gas‐liquid chromatography. Stearic acid was found to be the main fatty acid everywhere. Brain gangliosides of cold‐blooded animals contain lesser amounts of stearic and higher amounts of palmitic and monoenoic acids as compared to those of mammals.

Long‐chain bases were separated as trimethylsilyl derivatives. Large amounts (23‐48 per cent) of long chain bases with 20 carbon atoms were found in brain gangliosides of mammals while in those of cold‐blooded animals they constitute 3‐12 per cent of the total.

The comparison of the composition of gangliosides with that of cerebrosides and sulphatides indicates, that the fatty acid and long chain base composition of gangliosides from mammalian brain differs from that of other glycosphingolipids, whereas in brains of cold‐blooded animals they are much more similar.
FACTORS THAT AFFECT THE BINDING AND UPTAKE OF GABA BY BRAIN TISSUE1
Authors: Gottesfeld Zehava , Elliott K. A. C.
Published: December 2006

Abstract— As previously reported, when brain tissue was homogenized in isotonic solution and the suspension was centrifuged, less GABA was found in the sediment if the solution contained only sucrose than if it contained some NaCl. NaBr and Nal were as effective as the chloride. Less effective were Na2SOi, Na‐phosphate, and the chlorides of K, Li, choline, NHt, Ca or Mg. Ouabain and protoveratrine inhibited the extra binding promoted by NaCl in brain suspensions and inhibited the uptake of GABA by respiring slices of cerebral cortex; tetrodotoxin alone had no effect in either case but reversed the effect of protoveratrine. Considerable inhibition of the uptake of GABA by brain slices was observed with glutamic acid, imipramine, chlorpromazine, procaine, xylocaine or picrotoxin but not with acetylcholine, prostigmine, norepinephine, dopamine, chloral hydrate, chloretone, pentylentetrazol or methionine sulphoximine.
SYNTHESIS OF RADIOACTIVE ACETYLCHOLINE FROM [3H]CHOLINE AND ITS RELEASE FROM CEREBRAL CORTEX SLICES IN VITRO
Authors: Richter Judith A. , Marchbanks R. M.
Published: December 2006

Abstract— Guinea pig cerebral cortex slices were incubated for 60 min in a medium containing [3H]choline with or without the addition of 33 mM‐KCl for the last 30 min. KC1 caused the release into the medium of large amounts of both bioassayable and radioactive ACh, while at the same time their concentrations in the tissue decreased. The specific activity (d.p.m./pmol) of the ACh released by KC1 was greater than that released in control incubations, indicating that it comes from a newly synthesized, more radioactive store. The amounts of [3H]choline, [3H]ACh and the specific activity of tissue acetylcholine reached a plateau in the tissue 30 min after the addition of isotope. However isotopic equilibrium was not achieved because the specific activity of the ACh released, with or without KC1 in the subsequent 30 min, was less than the specific activity of the ACh remaining in the tissue. This implies the existence of a pool of ACh in the tissue which is turning over very slowly or is being synthesized from a less radioactive pool of choline. This pool of ACh does not contribute substantially to that released by KC1. Levorphanol at 10−3 M, as well as the analgesically inactive stereoisomer, dextrorphan, blocked the KCl‐stimulated release of both bioassayable and radioactive ACh. These drugs demonstrate the coupling of synthesis and release of ACh in cerebral cortex slices.
POLYSOME ANALYSIS OF EMBRYONIC SENSORY GANGLIA CULTURED IN VITRO WITH THE NERVE GROWTH FACTOR
Authors: Amaldi Paola
Published: December 2006

Abstract— The effect of the Nerve Growth Factor on the polysomal pattern of chick embryo sensory ganglia cultured in vitro has been studied. A two‐fold stimulation of polysome formation in NGF treated ganglia with respect to the control has been found after 3 to 15 hours of incubation. Double labelling experiments performed in order to detect qualitative changes of the polysomal pattern showed no differences between NGF treated and untreated ganglia after a 3‐hour incubation. Slight but significant differences in the poly‐somal‐monomer ratio (higher in the NGF treated ganglia) were found only for longer incubation time. Similar proportions of free and membrane bound polysomes have been found in NGF‐treated and control ganglia.
TOPOCHEMICAL ASPECTS OF NUCLEIC ACID AND PROTEIN METABOLISM WITHIN THE NEURON‐NEUROGLIA UNIT OF THE SPINAL CORD ANTERIOR HORN
Authors: Pevzner L. Z.
Published: December 2006

Abstract— Using a two‐wavelength modification of ultraviolet and visible cytospectro‐photometric methods, the content of nucleic acids per cell was determined in neuronal cytoplasm and glial satellite cell‐bodies from the spinal cord anterior horns in mice and rats. Mice which had been swimming for 3 and 4 h showed an increase in the content of RNA in the spinal motoneurons with no changes in the neuroglia. Stronger stimulation of the nervous system such as electrical skin irritation (20‐40 V, approx. 40 impulses/min) for 5 min resulted in an increase of RNA in the motoneurons of rat spinal cord and a decrease in the surrounding glia. Exhausting actions upon the nervous system (60 min irritation of rat paws by the electrical current, acute clonic convulsions in rats injected with cardiazol (pentamethylenetetrazol, metrazol) or initial free motor activity after 3 weeks of restraint of mice) induced a marked decrease of RNA content throughout the whole neuron‐neuroglia unit. After stimulation, return to normal amounts of RNA and protein was more rapid in glia than in neurons. After 1‐3 days rest the level of RNA was normal in motoneurons, but a decrease in glial RNA was shown. These trace changes in the glia are believed to reflect an adaptation mechanism in the nervous system at the cellular level. The relationship between neuronal and glial compartments within the neuron‐neuroglia unit is discussed; a supporting, homeostatic, secondary role of glial metabolism with respect to adequate reconstruction of neuronal metabolism is outlined.
FATTY ACID COMPOSITION OF CHOLESTEROL ESTERS IN BRAINS OF PATIENTS WITH SCHILDER'S DISEASE, GM1‐GANGLIOSIDOSIS AND TAY‐SACHS DISEASE, AND ITS POSSIBLE RELATIONSHIP TO THE β‐POSITION FATTY ACIDS OF LECITHIN 1
Authors: Eto Y. , Suzuki K.
Published: December 2006

Abstract— Cholesterol esters were isolated from cerebral cortex and white matter of patients with Schilder's disease, GM1‐gangliosidosis and Tay‐Sachs disease, and the fatty acid composition was determined by gas‐liquid chromatography. The fatty acid composition was similar among the three pathological conditions, but it was entirely different from that reported for cholesterol esters of normal brain. Lecithin and ethanolamine phospholipids were isolated from the same brain specimens, treated with snake venom phospholipase A, and the fatty acids at the a’and β‐positions of the glycerol moiety were determined separately. The fatty acid composition of cholesterol esters was similar to that of the β‐position fatty acids of lecithin of white matter in all samples, and was quite different from those of the a'‐position of lecithin, or of the a’or β‐position of ethanolamine phospholipids. The results indicate that the source of fatty acids for cholesterol esterification in nonspecific sudanophilic demyelination is different from that in normal brain, and that the most likely source is the β‐linked fatty acids of lecithin. There are two possible enzymic mechanisms; activation of phospholipase A and subsequent esterification of the liberated β‐position fatty acids to cholesterol, or direct transacylation by lecithin‐cholesterol acyl transferase.
GLUTAMYL AND ASPARTYL MOIETIES OF CEREBRAL PROTEINS: ENRICHMENT IN MEMBRANE‐CONTAINING MICROSOMAL SUBFRACTIONS
Authors: Tower D. B. , Wherrett J. R.
Published: December 2006

Abstract— The total mixed proteins (excluding proteolipids) were isolated from various tissues of the cat and from subcellular fractions of cat cerebral cortex and were compared for contents of total glutamyl and total aspartyl residues and total amide N. The proteins from renal cortex, testis and diaphragm were more acidic (proportionally more glutamyl and aspartyl residues with no increase of amide) than those from cerebral cortex, subcortical white matter and liver. Also the proteins isolated from cerebral cortical microsomes were more acidic than those from highly pure nuclear, mitochondrial and soluble subcellular fractions of cerebral cortex. Hepatic microsomal proteins gave very similar analyses.

Subfractionation of the microsomal preparations from cerebral cortex and liver into deoxycholate‐insoluble (ribosomal) and deoxycholate‐soluble (‘membrane’) fractions localized the acidic proteins to the latter, ‘membrane’ subtraction. The ribosomal proteins isolated from cerebral cortex (and liver) had an amino acid composition very similar to that reported previously for ribosomal proteins in a number of tissues from various species. Upon column chromatography on DEAE‐celluIose, the deoxycholate‐soluble (‘membrane’) subtraction of hepatic microsomes yielded a peak (eluted with 0‐2 M‐phosphate, pH 5‐6, plus 0‐5 M‐NaCl) that contained an exceptionally high proportion (30 per cent) of glutamyl and aspartyl residues. We suggest that such acidic proteins may be characteristic of membranes and may subserve important metabolic functions therein.
THE INFLUENCE OF IONIC STRENGTH ON THE INTERACTION OF QUATERNARY DRUGS WITH MAMMALIAN ACETYLCHOLINESTERASE IN RELATION TO POSSIBLE REGULATORY EFFECTS
Authors: Crone H. D.
Published: December 2006

Abstract— The effects of inorganic salts, gallamine triethiodide and (+)‐tubocurarine chloride on mammalian acetylcholinesterase (AChE) were examined. The results were obtained mainly from soluble erythrocyte AChE; particle‐bound and detergent‐solubilized rat brain enzymes were also used. Three aspects of AChE were examined, namely direct effects on activity, the recovery of activity of the diethylphosphorylated enzyme and thirdly the aggregation of the enzyme at low ionic strength as shown by chromatography on columns of Sepharose 6B. The action of gallamine on AChE was controlled by the substrate concentration and the ionic strength of the medium. Both inhibition and activation by gallamine could be observed, depending on the particular conditions used. All effects of gallamine disappeared when the ionic strength was raised to 015. The action of gallamine closely resembled the result of increasing ionic strength by adding NaCl, for in both cases the apparent affinity of AChE for substrate decreased and concomitantly the maximum velocity of hydrolysis increased. The phosphorylated enzyme recovered activity more rapidly when gallamine or tubocurarine were present, or when the ionic strength was increased. Aggregation of all enzyme forms was observed at low ionic strength; an increase to I= 015 dissociated AChE to the single molecular form. It was concluded that the mammalian enzymes closely resembled electric eel AChE. The possible methods by which regulation of AChE activity could occur are discussed in relation to these results.
PHOSPHOLIPID METABOLISM IN LIGHT AND DARK ADAPTED EXCISED RETINA
Authors: Urban P. F. , Dreyfus H. , Neskovic N. , Mandel P.
Published: December 2006

Abstract— The phospholipid composition of, and the incorporation of labelled phosphorus into the different phospholipids of rat and calf retina have been studied. The influence of various conditions, such as dark and light adaptation, during the preparation of retina, lipid extraction and incubation of retina with radioactive phosphorus was investigated.

The phospholipid composition of rat retina did not differ significantly from that of calf retina and the different conditions of preparation and incubation did not modify the distributions.

The specific radioactivities of the different phospholipids of calf and rat retina, incubated in the presence of 32P, distinguished in both species two groups of components characterized by the rate of labelling. Phosphatidic acid (PA) and inositol glycerophospholipids (PI) belonged to the first group and showed the highest uptake of labelled phosphorus; the second group, comprising choline glycerophospholipids (PC), serine glycerophospholipids (PS), sphingomyelin (SP), ethanolamine glycerophospholipids (PE) and cardiolipin (CL) showed low incorporation activities. Only SP was labelled differently in rat and calf retina. With the exception of PS, there was no evidence for the influence of light on the turnover of individual phospholipids. The finding that PS showed higher specific radioactivities when adaptation and incubation proceeded in the dark, seems to be of interest and needs further study.
EVIDENCE FOR INVOLVEMENT OF Ca2+ IN THE INCORPORATION OF 32Pi INTO THE PHOSPHATIDYLINOSITOL OF RAT DIAPHRAGM
Authors: Lennon Ana Maria , Steinberg H. R.
Published: December 2006

Abstract— Ethyleneglycol‐bis (β‐aminoethyl ether)‐N‐N'‐tetraacetic acid (EGTA) inhibited the incorporation of 32Pi into phosphatidylinositol (PI) in rat diaphragm incubated in Ca2+‐free Krebs‐Ringer medium. Only the labelling of the PI was altered, and no effects on the pool size of PI or on the incorporation of 32Pi into other phospholipids were observed. The effect of EGTA was concentration‐dependent and appeared to be related to its Caa+‐chelating properties; the inhibition of the incorporation of 32Pi could be completely reversed by the addition of excess Ca2+ but not Mg2+. The inhibitory effect of the EGTA was progressively enhanced by lengthening the preincubation of the tissue with EGTA, an observation suggesting that chelation of intracellular or membrane‐bound Ca2+, rather than extracellular Ca2+, was involved in the effect. In contrast to its inhibition of the incorporation of 32Pi EGTA enhanced the incorporation of [3H]inositol into PI, but this effect was accompanied by an appreciable increase in total uptake of [3Hlinositol by the tissue. Our results suggest that the level of intracellular Ca2+ plays a role in the regulation of the incorporation of 32Pi into PI. Addition of unlabelled α‐glycerophosphate to the incubation medium of tissues which had been preincubated with 2‐deoxy‐d‐glucose failed to cause a significant diminution in the inhibition by EGTA of the incorporation of 32Pi into PI. This experiment suggests, but does not prove, that the effect of EGTA was not at the level of incorporation of 32Pi into α‐glycerophosphate.
THE ROLE OF GABA METABOLISM IN THE CONVULSANT AND ANTICONVULSANT ACTIONS OF AMINOOXYACETIC ACID
Authors: Wood J. D. , Peesker S. J.
Published: December 2006

Abstract— At high dosage levels AOAA acted as a convulsant agent in mice and rats but in lower amounts it was an effective anticonvulsant agent against INH‐induced seizures, by tripling the time to the onset of the convulsions. AOAA elevated brain GABA levels as a result of a preferential inhibition of the GABA‐T enzyme system but, contrary to previous reports, the activity of the GAD enzyme system was also inhibited, even by relatively low dosage levels of AOAA. The state of excitability of the brain following the administration of AOAA was related, within the limits of the present study, to changes in GAD activity and GABA levels, but additional data are required before the relationship can be properly evaluated.
RECOVERY FROM GALACTOSE‐INDUCED NEUROTOXICITY IN THE CHICK BY THE ADMINISTRATION OF GLUCOSE1
Authors: Knull H. R. , Wells W. W.
Published: December 2006

Abstract— Chicks fed a diet containing 40% (w/w) galactose demonstrated convulsive activity after 52–54 h. However, they recovered from both physical and biochemical symptoms temporarily, following the intraperitoneal injection of glucose. The previously decreased levels of ATP and elevated levels of AMP in the brains of chicks fed galactose returned to normal within 20 min following the glucose treatment. During the recovery phase, plasma glucose content rose and brain glucose returned to the normal range, whereas the levels of brain galactose and its metabolites, galactitol and galactose 1‐phosphate, were unchanged. Moderate plasma hyperasmolality was induced in chicks fed the diet containing galactose and xylose or saline in the drinking water. Neurotoxicity was observed only in the group fed galactose, although brain glucose and glycogen were reduced in chicks fed xylose. In the brains of chicks fed xylose, xylitol was identified by gas‐liquid chromatography and mass spectrometry, and the amount was approximately 10 per cent of the amount of xylose simultaneously found in the brain. These studies support the viewpoint that dietary galactose exerts its acute neurotoxicity in chicks primarily by inhibition of glucose transport across the blood‐brain barrier.
EFFECTS OF AMINO‐OXYACETIC ACID ON [3H]GABA UPTAKE BY RAT BRAIN SLICES
Authors: Snodgrass S. R. , Iversen L. L.
Published: December 2006

Abstract— The effect of amino‐oxyacetic acid on the uptake of [3H]GABA by rat brain slices was studied. When added simultaneously with [3H]GABA, amino‐oxyacetic acid had no significant effect on [3H]GABA uptake. However, preincubation of brain slices with amino‐oxyacetic acid prior to addition of [3H]GABA produced inhibition of uptake, which increased with longer duration of preincubation. The inhibitory effect of amino‐oxyacetic acid was maximal at 2 mM concentration and concentrations sufficient to inhibit significantly GABA:glutamate transaminase (10‐‐6 M) had no effect on [3H]GABA uptake. D‐Cycloserine and β‐hydrazino‐propionic acid also inhibited [3H]GABA uptake, but the amounts required were considerably in excess of those needed to inhibit GABA:glutamate transaminase. 4‐Deoxypyridoxine inhibited [3H]GABA uptake, whether given in vivo or in vitro, and the inhibitory effect of amino‐oxyacetic acid was reversed with pyridoxine. GABA transport appears to be dependent on pyridoxal phosphate and interference with this function of the vitamin is suggested as the basis for the inhibitory effect of amino‐oxyacetic acid on [3H]GABA uptake.
INCORPORATION OF [14CICHOLINE INTO PHOSPHOLIPIDS IN THE ISOLATED PHRENIC NERVE‐DIAPHRAGM PREPARATION OF THE RAT1
Authors: McCarty Leslie P. , Knight Anita S. , Chenoweth M. B.
Published: December 2006

Abstract— The metabolism of [14C]choline has been studied in the isolated perfused phrenic nerve‐diaphragm of the rat. We obtained no evidence that acetylcholine was synthesized from labelled choline in this system. There was extensive incorporation of the choline into phosphatidylcholine and its precursors, cytidinediphosphocholine (CDP‐choline) and phosphocholine. Autoradiographic studies indicated that the lipids of myelin sheaths and nerve endings were the primary sites labelled.
HIGH AFFINITY UPTAKE OF TRANSMITTERS: STUDIES ON THE UPTAKE OF l‐ASPARTATE, GABA, l‐GLUTAMATE AND GLYCINE IN CAT SPINAL CORD
Authors: Balcar V. J. , Johnston G. A. R.
Published: December 2006

Abstract— The uptake of l‐aspartate, l‐glutamate and glycine each appeared to be mediated by two kinetically distinct systems with apparent Km's of the order of 10 ('high affinity') and 100 μM ('low affinity') in slices of cat spinal cord, whereas the uptake of GABA appeared to be mediated by a single system of high affinity. The high affinity uptake of these amino acids in slices of spinal grey matter was approximately 5 times faster than that in slices of spinal white matter. The high affinity uptake systems in the cord slices survived homogenisation of the tissue under conditions known to preserve nerve terminals. Subcellular fractionation studies indicated that osmotically‐sensitive particles of equilibrium density equivalent to that of 1.0 m‐sucrose were at least in part responsible for the uptake of these amino acids.

Inhibition studies indicated that three structurally specific systems of high affinity transported these amino acids:

specific for glycine—not inhibited by GABA or any of the other depressant amino acids found in cat spinal cord;

specific for GABA—not inhibited by glycine, taurine, l‐aspartate or l‐glutamate and (3) specific for l‐aspartate and l‐glutamate—not inhibited by glycine or GABA but strongly inhibited by various acidic amino acids such as l‐cysteate and l‐cysteine sulphinate.

The high affinity uptake of these amino acids was not inhibited by any of the known antagonists of the postsynaptic actions of these amino acids—strychnine (glycine), bicuculline and benzyl penicillin (GABA), methioninesulphoximine and l‐glutamate diethyl ester (l‐aspartate and l‐glutamate).

p‐Chloromercuriphenylsulphonate strongly inhibited the high affinity uptake of glycine and GABA but was much less effective as an inhibitor of l‐aspartate/l‐glutamate high affinity uptake. This is in good agreement with microelectrophoretic studies in which this mercurial was found to potentiate depression of neuronal firing induced by glycine and GABA much more readily than excitation induced by l‐aspartate or l‐glutamate. These findings suggest the importance of high affinity transport processes in the removal of amino acids from the synaptic environment.
ISOACCEPTOR tRNAs FOR GLUTAMATE, GLUTAMINE, ASPARTATE AND ASPARAGINE IN CALF BRAIN
Authors: Murthy M. R. V. , Roux Huguette , Thenot J. P.
Published: December 2006

Abstract— Glutamyl, glutaminyl. aspartyl and asparaginyl tRNAs of calf brain were analysed by reverse phase chromatography for isoacceptor tRNAs. The radioactivity profiles revealed two peaks for gluta‐mate. three for glutamine, two for aspartate and one for asparagine. Comparison of brain tRNAs with tRNAs from other sources showed that glutamate and aspartate tRNAs of brain closely resembled a majority of other tRNAs in the number and relative abundance of isoacceptors. Glutamine and asparagine tRNAs from different sources exhibited more marked differences.
CALCIUM METABOLISM IN ISOLATED BRAIN CELLS AND SUBCELLULAR FRACTIONS
Authors: Lazarewicz J. W. , Haljamäe H. , Hamberger A.
Published: December 2006

Abstract— The accumulation of calcium ions by brain mitochondria and microsomes and by fractions containing neuronal or glial cells has been studied in vitro with techniques involving 45Ca and ultramicro‐flame photometry. ATP and substrate‐supported calcium accumulation by brain mitochondria was of the same magnitude as for mitochondria from other organs. Brain microsomes accumulated calcium approximately 15 times less than brain mitochondria. Variations in Na+/K+ ratios and in ATP/ADP ratios had a more marked influence on microsomal uptake than on mitochondrial uptake. The passive Ca2+ binding by glial cells was higher than neuronal perikarya and synaptosomes. Also the calcium accumulation ability in cell suspensions was slightly higher for glial cells as compared to neuronal perikarya. The calcium uptake by glial cells was stimulated by high external K+ concentration, which also was the case for nerve endings. The uptake in neuronal perikarya was unaffected by variations in K+ concentration. A comparison between neuronal and glial mitochondria showed that both reach a steady state level of similar magnitude, but that the rate of initial accumulation was greater for glial mitochondria. A high glial calcium accumulation was also observed for the microsomal fraction.
PERMEABILITY OF MITOCHONDRIA FROM RAT BRAIN AND RAT LIVER TO GABA
Authors: Brand M. D. , Chappell J. B.
Published: December 2006

Abstract— For the GABA shunt to operate in rivo, GABA must be able to enter brain mitochondria. GABA causes reduction of intra‐mitochondrial NAD+; glutamate or 2‐oxoglutarate stimulate this reduction at concentrations at which they do not themselves cause reduction. This stimulation is not abolished by Triton X‐100. The rates of swelling of brain and liver mitochondria are similar in iso‐osmotic GABA and in several analogues. The rate of swelling is proportional to the concentration of GABA in the iso‐osmotic suspension medium. GABA penetrates 60% of the mitochondrial matrix volume, this value is unaffected by energizing the mitochondria. The activity of GABA‐oxoglutarate aminotransferase is not latent. We conclude that GABA diffuses into both brain and liver mitochondria as a species with no net charge at rates which are able to sustain maximum activity of the GABA shunt.
CYCLIC NUCLEOTIDE PHOSPHODIESTERASE OF THE BOVINE RETINA: ACTIVITY, SUBCELLULAR DISTRIBUTION AND KINETIC PARAMETERS
Authors: Chader G. , Johnson M. , Fletcher R. , Bensinger R.
Published: December 2006

Abstract— High phosphodiesterase activity for cyclic AMP and cyclic GMP was found in subcellular fractions of the bovine retina with more rapid hydrolysis of cyclic GMP than cyclic AMP in each fraction. Rod outer segments (ROS) and the supernatant fraction had highest activity. High enzyme activity remained associated with ROS membranes through several steps of purification by gradient centrifugation. A complex kinetic pattern was observed for cyclic AMP hydrolysis by the supernatant fraction yielding two values for Km; a simple kinetic pattern was observed with cyclic GMP hydrolysis in supernatant and for both cyclic nucleotides in preparations of purified outer segments. Phosphodiesterase activity of outer segments was enhanced by Mg2+. Mn2+ and inhibited by EDTA. Cyclic AMP had relatively little effect on the hydrolysis of cyclic GMP in supernatant or ROS while cyclic GMP inhibited hydrolysis of cyclic AMP in both fractions.
METAL CHELATES IN THE STORAGE AND TRANSPORT OF NEUROTRANSMITTERS: INTERACTIONS OF Cu2+ WITH ATP AND BIOGENIC AMINES1,2
Authors: Rajan K. S. , Davis J. M. , Colburn R. W.
Published: December 2006

Abstract— The thermodynamic stabilities of the coordinate binding of Cu2+ ion with adenosinetriphos‐phate (ATP) and several biogenic amines have been determined in aqueous model systems in an attempt to examine the possible correlation between metal‐amine binding and the in vivo affinities of the amines for granule‐binding. In each of the ternary chelate systems consisting of Cu2+‐ATP‐amine (1:1:1), the Cu2+ ion is preferentially bound by ATP in the pH range 3–5 with a stability constant of Log KML= 517. In the pH range 5–8 each of the biogenic amines coordinates with Cu2+ ‐ATP chelate to form the respective ternary chelate. The nature and strength of binding of fourteen different amines with Cu2+‐ATP have been evaluated on the basis of the stabilities of the ternary chelates. On the basis of the quantitative equilibrium data generated in this study, it appears that both pyrocatechol moiety and the ethanolamine side‐chain of the catechol amines are involved in the coordination of copper. The metal‐binding stabilities of the biogenic amines are then correlated with the molecular structure, donor basicities and the in vivo affinities of the amines for granule‐binding in order to rationalize the possible involvement of metal chelates in the monoamine binding, storage and transport.
INHIBITION BY APOMORPHINE OF DOPAMINE DEAMINATION IN THE RAT BRAIN
Authors: Chiara G. Di , Balakleevsky A. , Porceddu M. L. , Tagliamonte A. , Gessa G. L.
Published: December 2006

Abstract— Apomorphine (A) inhibited dopamine deamination by rat brain mitochondria, but did not influence catechol‐O‐methyltransferase (COMT) activity by brain homogenates. The administration of apomorphine (10mg/kg i.p.) to normal rats increased brain dopamine (DA) by 34 per cent and decreased homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) by 60 per cent. In rats treated with reserpine 15 min prior to A, the latter prevented the rise of cerebral HVA and DOPAC and the depletion of DA produced by the former. Finally, A decreased the L‐DOPA‐induced accumulation of HVA and DOPAC in the rat basal ganglia. These results indicate that A inhibits DA deamination by monoamine oxidase.

This inhibition seems to be specific since apomorphine did not influence 5‐HIAA levels in normal rats and prevented neither central 5‐HT depletion nor 5‐HIAA rise induced by reserpine.
METHYLATION OF MYELIN BASIC PROTEIN BY ENZYMES FROM RAT BRAIN
Authors: Jones Gwyneth M. , Carnegie P. R.
Published: December 2006

Abstract— In rat brain Methylase l activity (S‐adenosyl‐l‐methionine: protein‐arginine methyl‐transferase) is found predominantly in the cytoplasmic fraction, and it appears that several enzymes contribute to this activity. No evidence for the existence of two enzymes specific for the methylation of histone and myelin basic protein was found. The specific activity of Methylase I did not increase at the period of rapid synthesis of myelin basic proteins. Methylase I activity was strongly inhibited by S‐adenosyl‐l‐homocysteine.
METABOLIC COMPARTMENTATION IN THE BRAIN: METABOLISM OF A TRICARBOXYLIC ACID CYCLE INTERMEDIATE, [1,4‐14C] SUCCINATE, AFTER INTRACEREBRAL ADMINISTRATION
Authors: Mouhler. H. , Patel A. J. , Balaazs R.
Published: December 2006

Abstract— The metabolism of a tricarboxylic acid cycle (cycle) intermediate, [1.4‐'14C]succinate, was studied in the brain at 2 20 min after intracerebral injection. The oxidation of [14C]succinate was rapid, as shown by the incorporation of 14C into cycle amino acids which accounted for about 30 per cent and 70 per cent of the tissue ‐“Cat 2 and 10 min respectively. During the whole experimental period the specific radioactivity of glutamine was about three times higher than that of glutamate. Thus exogenous [14C]succinate elicited signs of metabolic compartmentation similar to those seen after the administration of short chain fatty acids or amino acids. A computer programme, based on data obtained previously on the metabolic compartmentation of acetate and of glucose in the brain, was used to simulate the kinetics of labelling of cycle amino acids after an input of [1.4‐14C]succinate. The correspondence of the simulated data with the experimental results was good in the first 10 min after injection, although the deviations were significant at later time points.

Incorporation of 14C into GABA was very low (< 1 per cent of the amino acid ‐14C) after the injection of [1.4‐14C]succinate. Further, labelled GABA formation was not detected in the decapitated rat brain labelled in vivo with [1.4‐14C]succinate 2 min beforehand. Since the oxidation of [l,4‐14C]succinate via the cycle yields unlabellcd GABA. whereas the reversal of the reactions in the GABA bypath may introduce 14C from succinate into the GABA pool, the results indicate that this reversal is negligible even under the most favourable conditions, i.e. post mortem when both the NADH/NAD+ ratios and [14C]succinate concentrations arc high. The observations are therefore consistent with the view that glutamate is the predominant and probably the only source of GABA carbon in the brain both in vivo and post mortem.
THE RELEASE IN VIVO OF [3H]ACETYLCHOLINE FROM CAT CAUDATE NUCLEUS AND CEREBRAL CORTEX BY ATROPINE, PENTYLENETETRAZOL, K+‐DEPOLARIZATION AND ELECTRICAL STIMULATION
Authors: Yaksh T. L. , Yamamura H. I.
Published: December 2006

Abstract— In the present experiments, the resting and stimulus evoked release of newly synthesized [3H]acetylcholine from the caudate nucleus, the cerebral cortex and the cerebellar cortex into the perfusate of the push‐pull cannula was studied in the unanesthetized, midpontine, pretrigeminally transected cat following infusion at the push‐pull site of [3H]choline. Separation of the metabolites in the perfusate revealed that after 20 min, approximately 20% of the recovered radioactivity in the sample was in a lipid fraction, about 10% was found to be phosphorylcholine and around 3% was observed to be incorporated into acetylcholine. The rest of the recovered radioactivity remained as choline. Electrical stimulation applied directly to the caudate nucleus, local potassium depolarization, atropine and pentylenetetrazol were all observed to result in a significant and stimulus dependent increase in the levels of [3H]acetyIchoIine, but not [3H]choline or [14C]urea in the effluent of the push‐pull cannula located in the caudate nucleus. A similar release of newly synthesized [3H]acetylcholine was observed following atropine and potassium stimulation in the cerebral but not the cerebellar cortex. The specificity of this evoked increase in the levels of [3H]acetylchoiine is substantiated by obtaining the release with stimuli having different modes of action, by the absence of stimulus evoked changes in the levels of other water‐soluble elements found in the perfusate and by the absence of an observable release of [3H]acetylcholine in perfusion experiments involving the cerebellum, a tissue not thought to have strong cholinergic innervation. The percentage increases in release of [3H] acetylcholine over baseline levels evoked by the various methods closely corresponded to those reported in the literature for authentic acetylcholine. This was taken to suggest that the neuronal pools containing endogenous acetylcholine and those containing newly synthesized acetylcholine, if not identical, were disposed to behave in the same manner following the activation of the synapse.
ALTERATION OF MYELIN BIOSYNTHESIS IN SLICES OF RABBIT SPINAL CORD BY ANTISERUM TO MYELIN BASIC PROTEIN AND BY PUROMYCIN 1
Authors: Pellkofer R. , Jatzkewitz H.
Published: December 2006

Abstract— Slices of rabbit spinal cord were incubated with [3H]tyrosine and [35SO4] in the presence of either 5% antiserum to myelin basic protein or 0.21 mM‐puromycin. The degree of incorporation of the precursors into the basic protein (BP), the proteolipid protein (PLP) and into sulphatides, as a representative lipid, in isolated myelin was investigated. Anti‐BP serum inhibited the incorporation of [3H]tyrosine into BP and PLP from 22 to 46% as compared to controls, whereas puromycin nearly completely inhibited incorporation. The incorporation of [35SO4] into sulphatides was inhibited by anti‐BP serum from 20 to 34% and by puromycin from 33 to 65% as compared to controls. These alterations were myelin‐specific as shown by the equal or even increased incorporation of the precursors into the homogenates of spinal cord. The results are discussed in relation to the interaction of lipids and proteins in membrane assembly.
UPTAKE OF GLUCOSE ANALOGUES BY RAT BRAIN CORTEX SLICES: Na+‐INDEPENDENT MEMBRANE TRANSPORT
Authors: Lund‐Andersen H. , Kjeldsen Christel S. , Hertz L. , Brondsted H. E.
Published: December 2006

Abstract— The glucose analogues 3‐O‐methyl‐D‐glucose and α‐methyl‐D‐glucoside were not metabolized in brain tissue.

The uptake of these two sugars into the intracellular compartment of brain cortex slices was investigated using media with normal and low Na+ concentration (replacement of all NaCl with choline Cl). The cellular transport was not Na+‐dependent. The transport mechanism clearly distinguished between the two sugars in both normal and low Na+ media.
THE EFFECT OF SPERMINE AND SPERMIDINE ON THE HYDROLYSIS OF ACETYLTHIOCHOLINE IN THE PRESENCE OF RAT CAUDATE NUCLEUS HOMOGENATE OR ACETYLCHOLINESTERASE FROM ELECTROPHORUS ELECTRICUS
Authors: Anand R. , Gore M. G. , Kerkut G. A.
Published: December 2006

Abstract— The effects of spermine and spermidine tetrahydrochloride on female Agus rat brain caudate nucleus homogenates, soluble acetylcholinesterase from the electric organ of Electrophorus electricus and acetylthiocholine iodide were studied. Measurements were made using an autoanalytical spectrophotometric method which measured the initial rate of reaction rapidly and accurately. Both polyamines interacted with the substrate, acetylthiocholine, causing an increase in the rate of its non‐enzymatic hydrolysis. Slight inhibitory effects on acetylcholinesterase were also observed. Combined effect of the polyamine on the substrate and the enzyme showed an inhibition at low and activation at high (above 1 mm) substrate concentrations.
TOPOGRAPHICAL AND SUBCELLULAR DISTRIBUTION OF CHOLINE ACETYLTRANSFERASE AND GLUTAMATE DECARBOXYLASE IN PIGEON OPTIC TECTUM
Authors: Henke H. , Fonnum F.
Published: December 2006

Abstract— The distribution of choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in different layers of the pigeon optic tectum and in some nuclei of the optic lobe have been investigated. About 40% of GAD and 25% of ChAT were found in the superficial part of tectum, but negligible activity was found in the stratum opticum. The highest GAD activity was found in layers 3‐7 (according to the nomenclature of Cajal, 1911) with a peak in layer 4. ChAT activity peaked in layers 3, 5. 8 and 10/11. Its distribution correlated well with the staining pattern of AChE, particularly in the superficial part of the tectum. The distribution of ChAT and GAD did not change significantly 4 weeks after enucleation. ChAT and GAD activities were high in the nucleus isthmi, pars parvocellularis (Ipc). The activity of GAD was also high in the nucleus intercollicularis (ICo), the other nuclei showed less activity of both enzymes.
A SENSITIVE ENZYMATIC‐ISOTOPIC METHOD FOR THE ANALYSIS OF TYRAMINE IN BRAIN AND OTHER TISSUES
Authors: Tallman John F. , Saavedra Juan M. , Axelrod Julius
Published: December 2006

Abstract— An enzymatic‐isotopic assay for the measurement of tyramine with a sensitivity of 1.0 ng has been developed. Using this assay, the endogenous content of tyramine in various tissues from adult rats has been determined. The highest tyramine content was found in rat heart atria, followed by salivary gland, kidney, and brain. Within the brain the distribution of tyramine is heterogeneous and the highest tyramine content was localized in the striatum.
PARTIAL PURIFICATION, PROPERTIES AND GLYCOPROTEIN NATURE OF ARYLSULPHATASE B FROM SHEEP BRAIN
Authors: Balasubramanian K. A. , Bachhawat B. K.
Published: December 2006

Abstract— A simple method has been developed for the partial purification of arylsulphatase B from sheep brain. This includes concanavalin A‐Sepharose affinity chromatography and ionic strength‐dependent binding and dissociation of the enzyme with Dextran Blue; by these methods the enzyme was purified 1344‐fold with 10% recovery. The partially purified enzyme was shown to be a glycoprotein and its kinetic properties were compared with that of purified arylsulphatase A from the same source.
ON THE STRUCTURE OF TWO NEW GANGLIOSIDES FROM BEEF BRAIN
Authors: Ghidoni R. , Sonnino S. , Tettamanti G. , Wiegandt H. , Zambotti V.
Published: December 2006

Abstract— Two new gangliosides were isolated in pure form from beef brain. They were provisionally named ganglioside G5a and G5b. Ganglioside GSa is a monosialoganglioside containing fucose. Its basic neutral glycosphingolipid core is the gangliotetraose ceramide: Gal (1 —> 3) GalNac (1—> 4) Gal (1 —> 4) Glc (1—>) ceramide, most likely with β‐linkages. Fucose is linked to the 2‐position of external galactose, N‐acetylneuraminic acid to the 3‐ position of internal galactose. Ganglioside G5b is a mixture of at least two isomeric disialogangliosides containing N‐acetylneuraminic acid and N‐glycolylneura‐minic acid. The major isomer has the following structure: NeuNac (α,2—>3) Gal (β,1—>3) GalNac (β, 1 —> 4) (NeuNglα, 2 —> 3) gal (β,1—>4) Glc (β,1 —>)‐ceramide. The minor isomer contains N‐acetylneur‐aminic acid and N‐glycolylneuraminic acid in an inverted linkage position.
METABOLIC RELATIONSHIPS BETWEEN MYELIN SUBFRACTIONS: ENTRY OF PROTEINS 1
Authors: Benjamins Joyce A. , Gray Marjory , Morell P.
Published: December 2006

Abstract— Partially purified myelin from brains of 17‐day‐old rats was separated into 4 subfractions on a discontinuous sucrose gradient by virtue of heterogeneity in density and particle size. The protein composition of each subfraction was determined by densitometry following separation of proteins on polyacrylamide gels in buffers containing sodium dodecyl sulphate. The major proteins studied included two basic proteins, proteolipid protein, the major high molecular weight protein (W) and a group of high molecular weight proteins.

The percentage of high molecular weight proteins decreased sequentially from fraction D to A, that of the W protein remained constant, while relative amounts of the two basic proteins increased. Proteolipid protein concentration also increased as a percentage of the total protein from fraction D to B, but the uppermost fraction. A, had a markedly lower amount than fraction B. At 1 h after intracranial injection of [3H]leucine, the specific radioactivity of the basic and proteolipid proteins decreased from fraction D to B, with proteolipid protein in fraction A again anomalous (specific radioactivity higher than expected). These results are consistent with (but do not prove) a precursor‐product relationship for individual proteins from denser to lighter subfractions, with the exception of myelin subfraction A.

Experiments involving time staggered injections of a [14C] and later a [3H] labelled amino acid gave data which demonstrated that the W and basic proteins were added simultaneously (or with delays of much less than 20 min) to all of the subfractions, while proteolipid protein was added sequentially, from lower to upper fractions on the gradient. This double isotope technique also confirmed our previous observations that proteolipid protein shows a lag in entry into myelin compared to basic protein.
DEVELOPMENTAL FEATURES OF CEREBELLAR HYPOPLASIA AND BRAIN BILIRUBIN LEVELS IN A MUTANT (GUNN) RAT WITH HEREDITARY HYPERBILIRUBINAEMIA 1
Authors: Sawasaki Y. , Yamada N. , Nakajima H.
Published: December 2006

Abstract— The marked cerebellar hypoplasia found in the homozygous (jj) Gunn rat with hereditary unconjugated hyperbilirubinaemia may provide an explanation of bilirubin neurotoxicity in vivo. In the jj Gunn rat. Purkinje cells were nearly selectively affected in the cerebellar cortex, and the cerebellar weight showed no increase after 10 days of age. The development‐dependency of the cerebellar lesion was supported by the observation that the cerebellar lobuli which developed earlier were less affected. Brain bilirubin in the developing jj Gunn rat was determined by a spectrophotometric method, and was found to be extremely low (1–3 μg). The level of brain bilirubin decreased after birth, and showed little correlation with the level of bilirubin free of albumin which correlated clearly with total serum bilirubin level even in the neonate. These findings suggest that there is an affinity of brain tissue for bilirubin associated with the blood‐brain barrier to bilirubin. No significant difference was found between the levels of bilirubin in the cerebellum and those of other brain regions in jj Gunn rat.

These results seem to imply that the development‐dependency of cerebellar hypoplasia in the jj rat may be due to the characteristic nature of rat cerebellar development, i.e. the postnatal neurogenesis. and not to changes in brain bilirubin levels. In the jj Gunn rat. cerebellar cell proliferation appears to be in some way affected by bilirubin during cerebellar development.
INFLUENCE OF LIPIDS ON THE ACTIVITY OF CEREBROSIDE‐SULPHOTRANSFERASE IN MOUSE BRAIN: A COMPARATIVE STUDY OF JIMPY AND NORMAL MOUSE BRAINS 1
Authors: Siegrist H. P. , Burkart T. , Steck A. J. , Wiesmann U. , Herschkowitz N. N.
Published: December 2006

Abstract— The effect of lipids other than the substrate cerebroside on the activity of cerebroside‐sulphotransferase (CST) in Jimpy and normal mouse brain was investigated.

The enzyme activity of an acetone‐treated microsomal preparation can be stimulated in the presence of the extracted lipids either with or without addition of exogenous cerebroside as a substrate.

The CST activity in the Jimpy mutant compared to that in normal animals differs from 18% in homogenate to approx 80% in solubilized or acetone‐extracted microsomes.

An addition of total lipid from normal mouse brain to microsomal preparations from which lipid has been removed by acetone results in a stimulation of Jimpy CST activity up to a value of 80% of normal mouse brain microsomes.

Both Jimpy and normal mouse brain CST can be also stimulated by the addition of single lipid components such as cholesterol and lecithin by 50% in normal and 100% in Jimpy brain microsomes.

These findings lead to the hypothesis that there is a lipid requirement for CST activity other than the substrate cerebroside.