bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES BY DNA‐RNA HYBRIDIZATION OF TRANSCRIPTIONAL DIVERSITY IN HUMAN BRAIN1
Authors: Grouse L. , Omenn G. A. , McCarthy B. J.
Published: October 2006

Abstract— Purified unique sequences of human DNA (from HeLa cells) were hybridized with various preparations of human brain KNA, to obtain estimates of the fraction of DNA transcribed. Values of 12 per cent were obtained for fetal brain increasing to 24 per cent for specific regions of adult brain. Right and left parietal and temporal cortical RNA gave similar plateau values but left frontal cortical RNA appeared to represent 2–3 times as much of the total genome as that from right frontal cortex. Lower values were obtained for fetal and adult brain stem and for RNA prepared from temporal cortex of a patient exhibiting gross cerebral atrophy. Attempts were made to assess the contributions of glial and neuronal cells by using human astrocytoma and mouse neuroblastoma RNA.
WATER‐SOLUBLE AND PENTANOL‐EXTRACTABLE PROTEINS IN HUMAN BRAIN NORMAL TISSUE AND HUMAN BRAIN TUMOURS, WITH SPECIAL REFERENCE TO S‐100 PROTEIN
Authors: Haglid K. G. , Stavrou D.
Published: October 2006

Disc electrophoretic separation of water‐soluble and pentanol‐extractable protein from normal human brain and human brain tumours (glioblastoma, neurinoma and medulloblastoma) on 10 per cent polyacrylamide gels showed minor differences between tissues. After disc electrophoresis ependymomal tumour cells contained high concentrations of a rapidly migrating anodic protein fraction which was immunologically distinct from S‐100 protein. After electrophoresis of normal brain grey matter in a continuous buffer system, a rapidly migrating anodic protein fraction which was immunologically distinct from S‐100 protein was found, and this protein fraction had a similar relative mobility to that of ependymomal tumour cells. This protein fraction was present to a low extent in human normal white matter, but absent from neurinoma and glioblastoma.

In a continuous buffer system at least two separable protein fractions, immunologically equivalent to S‐100 protein, were observed in normal human brain. The more anodic of these two fractions was shown to be present in relatively high amounts in neurinomas, and may be of Schwann cell origin. Additional S‐100 protein could be extracted from residual material remaining after removal of water‐soluble proteins; 2.8‐10 per cent of the water‐soluble S‐100 in normal material, and 0.1‐0.6 per cent of that present in tumour material, was extractable from the water‐insoluble residue by pentanol.
DEVELOPMENTAL TRANSITIONS IN UPTAKE OF AMINO ACIDS BY SYNAPTOSOMAL FRACTIONS ISOLATED FROM RAT CEREBRAL CORTEX
Authors: Peterson N. A. , Raghupathy E.
Published: October 2006

Developmental changes in mechanisms of synaptosomal amino acid transport have been studied in rat cerebral cortex. Well‐defined changes over an age continuum could be observed in both the rates of amino acid accumulation and the effects of Na+ on the accumulation. The uptakes of five amino acids (threonine, serine and valine in Na+‐free medium, aspartic acid and proline in Na+‐containing medium) increased progressively with the age of the animal, whereas the uptakes of leucine and arginine (in Na+‐free medium) decreased steadily. The uptake of serine or threonine by synaptosomal fractions prepared from newborn rats was markedly dependent on the presence of Na+in the incubation media. Na+exerted progressively less effect on the accumulation process with continuing postnatal development and to some extent inhibited uptake by fractions obtained from rats older than about 15 days. Na+significantly enhanced the accumulation of glycine in fractions from newborn and adult rats, but had only a slight effect in fractions prepared from 12 to 17‐day old rats. A detailed study of the accumulation of glycine indicated that the synaptosomal transport of this amino acid proceeded by two independent systems, one of which was totally dependent on external Na+and the and adult animals than in fractions from 12 to 17‐day‐old rats, wheras the Na+‐independent system was most active during this latter period of development. The decline in the Na+‐independent accumulation of glycine from about the 15th day to adulthood was characterized by a decrease in the Vmax. and an increase in the Km.
ELECTROPHORESIS OF GLUTAMIC ACID DECARBOXYLASE (EC 4.1.1.15) FROM MOUSE BRAIN IN SODIUM DODECYL SULPHATE POLYACRYLAMIDE GELS1
Authors: Matsuda T. , Wu J.‐Y. , Roberts E.
Published: October 2006

Electrophoretically and ultracentrifugally homogeneous glutamic acid decarboxylase purified from mouse brain showed multiple protein bands after electrophoresis in SDS polyacrylamide gel. The positions and intensities of the multiple bands were constant despite different treatments of the enzyme with various concentrations of SDS, β‐mercaptoethanol, and urea at different temperatures. The major band had an apparent molecular weight of approximately 60,000 daltons and there were three minor bands of molecular weights, about 120,000, 90,000, and 75,000 daltons, respectively. The molecular weights of almost all bands were approximately integral multiples of 15,000. The possible subunit structure of this enzyme has been discussed in the light of the latter data and data previously reported from ultracentrifugation and gel filtration studies. We suggest that this enzyme may be a hexamer consisting of 15,000‐dalton sub‐units and that dissociation of these sub‐units in SDS is accompanied by reassociation into a variety of aggregates, the probability of whose formation is determined by structural features that are more important than the differences encountered under the environmental conditions employed in these studies.
INCREASE OF NORADRENALINE METABOLISM FOLLOWING ELECTRICAL STIMULATION OF THE LOCUS COERULEUS IN THE RAT1
Authors: Walter D. S. , Eccleston D.
Published: October 2006

A sensitive gas–liquid chromatography method is described for measuring both free and conjugated 4‐hydroxy‐3‐methoxyphenyl glycol (HMPG) in brain, which is applied to study the turnover of noradrenaline (NA) in brain when one Locus coeruleus (LC) is stimulated electrically. Stimulation was found to produce a rise in total HMPG on the ipsilateral side of brain when the current was sufficiently low to obviate current spread to the opposite LC. This suggests an increase in turnover of NA on electrical stimulation.
EFFECT OF HALOTHANE ON CO2 PRODUCTION FROM GLUCOSE, FRUCTOSE AND PYRUVATE IN RAT CEREBRAL CORTICAL SLICES1
Authors: Husain S. , Paradise R. R.
Published: October 2006

Abstract— The effect of halothane on rat cerebral cortical metabolism was studied by measuring 14CO2 production from various [14C]‐labelled substrates. Glucose metabolism was depressed by clinically‐used concentrations of halothane (0.35 mm; 1.65 MAC) which did not significantly affect the metabolism of fructose or pyruvate. We concluded that halothane blocked an early step(s) in glycolysis preceding phosphofructokinase. Hexokinase was considered unlikely as the site of blockade, leaving glucose uptake or the glucose phosphate isomerase step as the most likely site(s). Higher concentrations of halothane (0.7 mm; 3.3 MAC) were required to block the metabolism of fructose or pyruvate to CO2. This action of halothane was attributed to the known inhibition by halothane of electron transport processes.
ACTIVE POTASSIUM TRANSPORT AND [Na++ K+]ATPase ACTIVITY IN CULTURED GLIOMA AND NEUROBLASTOMA CELLS
Authors: Kimelberg H. K.
Published: October 2006

—The ouabain‐sensitive K+ uptake and ATPase activities of cultured glioma and neuroblastoma cells were studied. Both cell lines showed ouabain‐sensitive K+ uptake which correlated with the level of [Na++ K+]ATPase activity found in the respective total cell homogenate. The glioma cells had a 2.1‐fold higher rate of K+ uptake than neuroblastoma cells, and a 2.4‐fold higher [Na++ K+]ATPase activity. In the presence of ouabain neuroblastoma cells released K+ and took up Na+ in a 1:1 ratio. These results are compared and contrasted with similar studies on brain tissue and isolated cells. It is suggested that the cultured cell lines may serve as good models for the cation transport properties of their tissue counterparts.
ACUTE HYPERCAPNIA AND BRAIN ENERGY STATE IN SUSTAINED HYPERAMMONAEMIA
Authors: Hindfelt B.
Published: October 2006

Abstract— The effect of acute hypercapnia upon the energy state of the brain in sustained hyperammonaemia was evaluated in lightly (N2O) anaesthetized rats. No significant changes occurred in the high energy phosphates (phosphocreatine, ATP, ADP, and AMP) despite a fourfold increase in the ammonia content and a 50 per cent reduction in the total α‐ketoglutarate content. It is concluded that brain tissue maintains energy homeostasis in hypercapnic hyperammonaemia.
INVOLVEMENT OF MANNOSYL‐PHOSPHORYL‐DOLICHOLS IN MANNOSE TRANSFER TO BRAIN GLYCOPROTEINS
Authors: Wolfe L. S. , Breckenridge W. C. , Skelton P. P. C.
Published: October 2006

Abstract— Mannose was transferred from GDP‐[14C]mannose by homogenates of embryonic chick and adult rat brain to mannolipids with properties identical to manriosyl‐phosphoryl‐dihydropolyisoprenols. Embryonic chick brain formed six‐fold larger quantities of mannolipid than adult rat brain. The reaction was stimulated by Mn2+ ions and Triton X‐100 but inhibited by EDTA. Phosphoenolpyruvic acid had no effect on the reaction. A crude mitochondrial fraction was two to three times more active than the microsomal fraction. All radioactivity in the mannolipid could be displaced by the addition of non‐radioactive GDP‐mannose. The endogenous lipid acceptor in brain was readily labelled in vivo by injection of [3H]mevalonate into the amniotic sac of 7‐day‐old embryos. The mannolipid formed had the properties of an acidic phospholipid on column and TLC, was stable to dilute alkali but readily cleaved by dilute acid. Synthesis was markedly stimulated by the addition of pig liver or calf brain dolichol phosphate in the presence of Triton X‐100 and Mn2+. The mannolipid so formed displayed chemical characteristics identical to the endogenous lipid acceptor. Incubation of the purified radioactive mannolipid with the ‘post‐nuclear’ fraction from 14‐day‐old embryonic chick brain in the presence of EDTA and Triton X‐100 resulted in the transfer of 40‐50 per cent of the radioactive mannose to protein and 40‐45 per cent to water soluble compounds. The efficiency of transfer of radioactivity from endogenously formed mannolipid with or without the addition of dolichol phosphate was similar to exogenously added highly purified mannolipid. These results are compatible with the hypothesis that synthesis of the mannose core of brain glycoproteins involves the synthesis first of mannosyl‐phosphoryl‐dolichols followed by transfer of the mannose to glycoprotein.
DELTA‐AMINOLEVULINIC ACID UPTAKE BY RABBIT BRAIN CEREBRAL CORTEX
Authors: Becker D. M. , Kramer S. , Viljoen J. D.
Published: October 2006

Abstract— δ‐Aminolevulinic acid (δ‐ALA) was taken up by rabbit brain cortical slices to a concentration greater than that in the surrounding medium. The process responsible for this accumulation of δ‐ALA shows many of the properties characteristic of an active transport system. δ‐ALA is taken up by a system which exhibits some allosteric kinetic properties, and is specific to a relatively high degree.
REGIONAL DISTRIBUTION OF PUTRESCINE, SPERMIDINE AND SPERMINE IN RELATION TO THE DISTRIBUTION OF RNA AND DNA IN THE RAT NERVOUS SYSTEM
Authors: Seiler N. , Schmidt‐Glenewinkel T.
Published: October 2006

—Putrescine, spermidine, spermine, RNA, DNA and protein concentrations were determined in 14 parts of the rat nervous system. If the concentrations are expressed in DNA units, putrescine and spermidine concentrations change concomitantly in the different brain parts, with the exception of hypothalamus, where relatively higher putrescine than spermidine concentrations are observed. The constancy of putrescine/spermidine ratios indicates the value of putrescine concentration as an index of spermidine biosynthesis. Spermidine correlates with RNA, except in medulla, spinal cord and peripheral nerves. It is assumed that the relative excess of spermidine in these structures indicates an additional functional role. Spermine/DNA ratios are remarkably constant in the diencephalic and telencephalic regions; they are also nearly constant, but significantly lower in midbrain, medulla, spinal cord and cerebellum. This observation gives additional support for the preferential interrelation of spermidine with RNA and spermine with DNA; i.e. for different functional roles of these two narrowly related polycations.
A RADIOIMMUNOASSAY FOR MYELIN BASIC PROTEIN AND ITS USE FOR QUANTITATIVE MEASUREMENTS
Authors: Cohen S. R. , McKhann G. M. , Guarnieri M.
Published: October 2006

—A specific radioimmunoassay (RIA) for myelin basic protein is described which is sensitive to 10−9 g of basic protein. The amount of basic protein detected in isolated myelin by the RIA and by SDS‐gel electrophoresis and spectrophotometric quantitation agree to within experimental error. In contrast to isolated myelin, the major portion of the basic protein in fresh tissue is not accessible to its antibody. It is shielded from its antibody in a complex which is disrupted by heat, organic solvents, and various detergents. Maximum antibody binding was obtained with tissue heated to 100°C for 10 min. It is possible to calculate that the RIA quantitatively detects basic protein in boiled tissue. Boiled adult rat brain contains approximately 2·5 μg of basic protein/mg wet wt of cerebral cortex. The antibody to basic protein has no capacity to bind non‐neural tissues.
THE FORMATION OF CDP‐DIGLYCERIDE BY ISOLATED NEURONAL NUCLEI
Authors: Thompson R. J.
Published: October 2006

—A population of neuronal nuclei isolated from the rabbit cerebral cortex actively incorporates cytidine‐5′‐triphosphate into an acid‐insoluble product, the incorporation is stimulated by magnesium or manganese ions and appears to utilize CTP directly as substrate. Other nucleoside triphosphates stimulate CTP incorporation at low substrate concentrations, apparently by preventing CTP breakdown, while higher concentrations of nucleoside triphosphates strongly inhibit CTP incorporation at either low or saturating substrate concentrations. CTP incorporation appears to be unrelated to RNA synthesis in that it exhibits a different pH and divalent cation optimum, is unaffected by inhibitors of RNA synthesis, and is strongly inhibited by low concentrations of detergent but not by preincubation of nuclei at 37°C. The product of CTP incorporation is almost entirely soluble in acidified lipid solvents and is not sensitive to digestion by RNAase under conditions where the enzyme can digest newly synthesized RNA. CTP incorporation is markedly stimulated by phosphatidic acid, the stimulated incorporation showing the same characteristics as the unstimulated incorporation, and is inhibited by inositol. Alkaline hydrolysis of the product releases the great majority of radioactivity as 5′‐CMP as judged by chromatography and by 5′‐nucleotidase action. The product of CTP incorporation migrates with synthetic CDP‐diglyceride in five solvent systems. It is concluded that under optimal conditions for CTP incorporation, less than 5% of the incorporated CTP can be included in a polynucleotide chain, this small proportion of the total incorporation could either represent residual RNA synthesis or the formation of poly (C) with an average chain length of less than 3 residues. Under optimal conditions the great majority of CTP incorporation by neuronal nuclei in the presence of either magnesium or manganese ions represents the formation of the unique liponucleotide CDP‐diglyceride.
INHIBITION OF 5′‐NUCLEOTIDASE IN RAT BRAIN BY METHYLXANTHINES
Authors: Tsuzuki Junji , Newburgh R. W.
Published: October 2006

—Rat brain 5′‐nucleotidase (EC 3.1.3.5) is inhibited by methylxanthines such as theophylline. Inhibition of the 5′‐nucleotidase by theophylline appears more efficient than the inhibition of cAMP phosphodiesterase by this drug. A similar inhibition is observed with caffeine, theobromine, 7′‐methyl‐xanthine and 1‐methylxanthine.
CIS‐ AND TRANS‐4‐AMINOCROTONIC ACID AS GABA ANALOGUES OF RESTRICTED CONFORMATION
Authors: Johnston G. A. R. , Curtis D. R. , Beart P. M. , Game C. J. A. , Mcculloch R. M. , Twitchin B.
Published: October 2006

Abstract—

Cis‐4‐aminocrotonic acid, an analogue of GABA in a folded conformation, appears not to act as a GABA analogue with respect to bicuculline‐sensitive postsynaptic receptors, ‘high affinity’ GABA uptake and GABA: 2‐oxoglutarate aminotransferase in the mammalian central nervous system. On the other hand, trans‐4‐aminocrotonic acid, an analogue of GABA in an extended conformation, acts as efficiently as GABA with respect to each of the above systems, indicating that extended rather than folded conformations of GABA are likely to be important in the interaction of GABA with the specific macromolecules concerned.
MOLECULAR FORMS OF ACETYLCHOLINESTERASE: THEIR DE NOVO SYNTHESIS IN MOUSE NEUROBLASTOMA CELLS
Authors: Rieger F. , Faivre‐Bauman Annie , Benda P. , Vigny M.
Published: October 2006

Abstract—

Rat mouse AChE molecular forms are indistinguishable with respect to their sedimentation coefficients and their evolutive proportions during brain maturation. Among rat or mouse erythrocytes, rat C6 glial cells, and mouse 2A and NS 20 neuroblastoma cells, only neuroblastoma cells showed both the ES and HS molecular forms with a 1:1 proportion for NS 20 cells. All these cells lack a third molecular form (16S), which is present in rat and mouse superior cervical ganglia. After irreversible inhibition of pre‐existing NS 20 neuroblastoma AchE, the ES form is first synthesized (de novo synthesis). The HS form begins to appear after a lag time of several hours and represents, 24 h after inhibition, only 15% of the total recovered activity, which is near the initial level. The initial relative proportions return by 2 to 3 days after inhibition. The recovery of the HS form is, for the most part, blocked by actinomycin D, which does not block the recovery of activity itself, which remains as an ES form.

It seems that integration of the ES form into the HS form more probably depends on the synthesis of a new messenger RNA, which is required for the synthesis of either new AChE polypeptide chain, polymerization initiating protein or activating enzyme.
PROPERTIES OF TYROSINE HYDROXYLATION IN LIVING MOUSE NEUROBLASTOMA CLONE N1E‐115
Authors: Richelson E.
Published: October 2006

Abstract—

Tyrosine hydroxylation was studied in intact cells of mouse neuroblastoma clone N1E‐115 which have high levels of tyrosine 3‐monooxygenase (EC 1.14.16.2) and which have been fully characterized for tyrosine transport. Measurement of [3H]OH formed from L‐[3.5‐3H]tyrosine in the medium was the method of assay and [3H]OH formed was stoichiometric with the formation of L‐[3H]3.4‐dihydroxyphenylalanine. Tyrosine hydroxylation was dependent on time of incubation, cell number, and the concentration of [3H]tyrosine in the medium. From velocity vs. [3H]tyrosine concentration experiments. two apparent Km, values were obtained: Km1= 10 ± 2μM: Km2= 140 ± 10μM. Substrate inhibition occurred with tyrosine concentrations between 20 and 50 μM. The reaction was twice as fast at pH 5.5 as at pH 7.4. α,α′‐Dipyridyl (1 mM) caused major inhibition (75%) when [3H]tyrosine concentration was 10 μM. L‐3‐Iodotyrosine was a competitive inhibitor with Ki= 0.3 μM. Dopamine was a non‐competitive inhibitor with Ki= 500 μM. 1‐Norepinephrine had no effect. These results show that the hydroxylation of tyrosine by living N1E‐115 cells has many of the properties of the reaction catalyzed by purified tyrosine 3‐monooxygenase from normal tissue.
CATECHOL‐O‐METHYLTRANSFERASE IN RAT ERYTHROCYTE AND THREE OTHER TISSUES: COMPARISON OF BIOCHEMICAL PROPERTIES AFTER REMOVAL OF INHIBITORY CALCIUM1
Authors: Quiram D. R. , Weinshilboum R. M.
Published: October 2006

Abstract—

The biochemical characteristics of soluble catechol‐O‐methyltransferase (COMT) activity in rat erythrocytes were compared with the properties of the soluble enzyme in rat liver, heart, and brain. COMT was measured by a procedure that avoided artifacts of some other assay procedures including inhibition of the enzyme by endogenous calcium. After the removal of calcium from the reaction mixture the apparent Michaelis‐Menten constants for the two cosubstrates of the COMT reaction, S‐adenosyl‐1‐methionine (SAM) and 3,4‐dihydroxybenzoic acid (DBA), were similar in tissue preparations of rat liver, brain, heart and blood. The apparent Km, values for the four tissues ranged from 5.7 to 6.7 × 10−6M and from 0.9−1.4 × 10−4M for SAM and DBA, respectively. The optimal pH and the optimal concentration of magnesium for the assay of red blood cell COMT were also similar to those for the enzyme in the three other rat tissues. After the removal of endogenous calcium, COMT activity in all four tissues was inhibited by the addition of calcium, and the [CaCl2] necessary to inhibit the enzyme activity 50% was 3−5 × 10−4M in all cases. The relative activities of COMT in the rat heart, brain, erythrocyte, and liver when expressed per g tissue or per ml of packed red blood cells were 1 to 1.15 to 1.58 to 140, respectively.
THE PHOSPHORYLATION OF BRAIN MICROTUBULAR PROTEINS IN SITU AND IN VITRO
Authors: Reddington M. , Tan L. P. , Lagnado J. R.
Published: October 2006

Abstract—

The phosphorylation of microtubular proteins isolated by reassembly in vitro from slices of guinea‐pig cerebral cortex labelled with [32P]orthophosphate was investigated. Under the conditions tested, both and the α and β forms of tubulin contained metabolically‐active P which accounted for about one third of the total 32P incorporated into protein; the remaining protein‐bound 32P was associated with 3–4 minor high MW components co‐purifying with tubulin during two cycles of assembly4sassembly. Microtubular protein prepared in this way contained approx. 0.8 mol of alkali‐labile P/mol of tubulin dimer (M.W. 110,000).

In vitro studies showed that reassembled microtubular protein preparations catalysed the incorporation of up to 0.55 mol of P/mol of tubulin dimer during incubation with Mg2+ and [γ32P]ATP. The reaction was linear during the first 30 min of incubation at 37°C. Cyclic AMP (10 μm, final concentration) caused a transient increase in the initial rates of tubulin phosphorylation. Little label was incorporated into the minor high M.W. components under these conditions. The in vitro phosphorylation of microtubular protein increased in a non‐linear manner with respect to protein concentration: this was in contrast to earlier experiments showing linear kinetics when chromatographically isolated tubulin was tested for intrinsic kinase activity. Isolated microtubular protein preparations bound [3H]GTP, [3H]ATP and to a lesser extent, [3H]cyclic AMP, and exhibited Ca2+‐ATPase activity (up to 60pmol Pi released min/mg protein at 37°C).
THE EFFECT OF SULFHYDRYL REAGENTS ON THE TITYUSTOXIN‐INDUCED ACETYLCHOLINE RELEASE IN RAT BRAIN SLICES1
Authors: Oliveira Z. E. G. , Heneine I. F. , Gomez M. V.
Published: October 2006

Abstract— Pre‐treatment of rat brain slices with organic mercurials prevents the increased acetylcholine release induced by tityustoxin. This inhibition is reversed by dithiothreitol. N‐Ethylmaleimide blocks the tityustoxin effect irreversibly. Simultaneous incubation with mercurials and toxin reveals a competition of both ligands for a membrane sulfhydryl group apparently required for tityustoxin activity.
SUBCELLULAR DISTRIBUTION OF TAURINE AND CYSTEINE SULPHINATE DECARBOXYLASE ACTIVITY IN OX RETINA
Authors: Macaione S. , Tucci G. , Luca G. De , Di Giorgio R. M.
Published: October 2006

Abstract– Taurine levels have been determined in primary and secondary subcellular fractions of ox retina and pigment epithelium.

About the 79.5% of recovered taurine is located in the soluble fraction (S3), while the remainder is associated with the particulate components. In the secondary subcellular fractions, taurine is primarily associated with the synaptosomal fraction.

Cysteine sulphinate decarboxylase is predominantly associated with particulate components of retinal cells. About the 50% of the recovered enzyme activity of crude mitochondria is present in the synaptosomal fraction.
HETEROGENEITY OF ACETYLCHOLINESTERASE IN NEUROBLASTOMA
Authors: Chang C.‐H. , Blume A. J.
Published: October 2006

Abstract– Multiple forms of acetylcholine hydrolyzing activity have been observed in Triton X‐100 treated homogenates of mouse neuroblastoma cells. All these forms appear to be the true acetylcholinesterase, AChE (EC 3.1.17): they are substrate‐inhibited; hydrolyze acetylcholine > acetyl‐β‐methylcholine ≫ butrylcholine and are preferentially inhibited by specific AChE inhibitors. Almost all of the cell AChE activity is membrane associated, but readily ‘solubilized’ by Triton X‐100 and as such appears free of membrane contamination. With the aid of affinity chromatography the ‘solubilized’ neuroblastoma AChE has been partially purified (490‐fold) to a specific activity of 34,300 nmol/min/mg protein.

Four active neuroblastoma AChE species appear upon acrylamide gel electrophoresis (with MWs of 64,000; 116,000; 186,000 and 284,000) while three species (4S, 6S and 9.6S) have been found upon sucrose gradient sedimentation analysis. We have determined that the 4S form migrates on acrylamide as the 116,000 MW species and the 9.6S form contains, in equal amounts, the 186,000 and 284,000 MW acrylamide species. Numerous active AChE forms are seen on Sepharose 6B chromatography. From comparing the crude, 4S, 9.6S and partially purified AChEs on acrylamide gels, sucrose gradients and Sepharose, mouse neuroblastoma appears to contain active AChE units which are capable of multiple types of dissociation and reassociation. An attempt is made to correlate all the observed AChE forms as well as relate this data to that known about AChE obtained from other sources.
RELEASE OF GLUTAMATE AND OTHER AMINO ACIDS FROM ARTHROPOD NERVE–MUSCLE PREPARATIONS
Authors: DAOUD A. , Miller R.
Published: October 2006

—A study has been made of the release of glutamate and other amino acids from perfused leg preparations from Carcinus and Schistocerca, at rest and during stimulation of motor nerves to the leg muscles. Stimulation caused an increase in release af many amino acids. No evidence was obtained to link glutamate release from such preparations with synaptic function. If release of transmitter glutamate is to be demonstrated in arthropods, techniques must be devised to avoid contamination with large quantities of non‐transmitter glutamate.
BINDING OF [3H]KAINIC ACID, AN ANALOGUE OF l‐GLUTAMATE, TO BRAIN MEMBRANES
Authors: Simon J. R. , Contrera J. F. , Kuhar M. J.
Published: October 2006

—The specific binding of [3H]kainic acid to synaptic membranes from rat brain was saturable with a dissociation constant of about 60 nm. The apparent maximal number of binding sites was about 1 pmol/mg protein. The most effective displacer of specific [3H]kainic acid binding was quisqualic acid, a powerful excitant which is structurally similar to l‐glutamate. However, quisqualic acid was one‐third as potent a displacer as kainic acid itself. l‐Glutamate was the next potent in displacing [3H]kainic acid binding, but also was less effective (1/25) than kainic acid itself. All other compounds including suspected neurotransmitters were at least an order of magnitude lower in potency compared to l‐glutamate. When various tissues and brain regions were tested for specific [3H]kainic acid binding, we found the specified binding was localized to grey matter in the brain. In studies of subcellular fractionation of the brain, we found that crude synaptosomal membrane preparations were most enriched in specific [3H]kainic acid binding. Specific [3H]kainic acid binding in various regions of the rat brain varied 5‐ to 6‐fold.
CYTOCHROME REDOX POTENTIAL DEPENDENCE ON SUBSTRATE IN RAT CEREBRAL CORTEX SLICES: IMPORTANCE OF CYTOPLASMIC NAD(P)H AND POTASSIUM
Authors: Bull R. J.
Published: October 2006

—Using dual‐wavelength absorbance spectrophotometry, the ability of various substrates to produce and maintain a redox potential in the cytochrome chain of rat cerebral cortex slices was studied. In general, the ability to reduce the cytochromes parallels previously reported capabilities of the substrates to support metabolic responses to stimulation. The steady‐state kinetics of cytochrome reduction by glucose or lactate displayed a very sharp dependency upon concentration in the regions of 1 or 3 mm, respectively. This was in contrast to a near linear reduction of the cytochromes with concentrations of pyruvate over a range of 1–10 mm. The production and maintenance of a cytochrome redox potential was found to be at least partially dependent upon the presence of potassium (3 mm in the incubation media). Reduction of the cytochromes attributable to potassium was inhibited by ouabain, indicating that intracellular potassium was the important variable.

Addition of glucose or lactate to 'starved’ tissues was found to result in a complex cycle of oxidation and reduction of tissue NAD(P)H. A small initial reduction of NAD(P) was followed by an oxidation of NAD(P)H which occurred in an all‐or‐none fashion with reduction of the cytochromes. The oxidation of NAD(P)H and reduction of cytochrome b appeared to occur with a similar time course.

Respiratory changes following addition of glucose were complex in time course, but established a new steady‐state rate 0.41 μmol/g per min above the preaddition rate in 10–12 min. Despite a similar level of reduction in the cytochrome chain, stimulation of respiration by pyruvate was only about 50% of the rate observed with addition of glucose. However, stimulation of respiration by addition of equim concentrations of pyruvate and lactate was found to be additive, producing a 0.48 μmol/g per min increase in the steady‐state rate of oxygen consumption.

These data seem to support the conclusion that the cytoplasmic reducing equivalent derived from the initial oxidation of glucose or lactate plays an important, perhaps regulatory, role in the respiration of cerebral tissues.
CHOLINE UPTAKE BY CHOLINERGIC NEURON CELL SOMAS
Authors: Suszkiw J. B. , Beach R. L. , Pilar G. R.
Published: October 2006

The cellular compartments of ciliary ganglia take up choline by a single, saturable process with Km=7.1 × 10−5 M and Vmax= 4.66 pmol/min per ganglion: Denervation of the ganglia and the resultant degeneration of nerve terminals caused no significant decrease of the rate of accumulation of choline by the ganglia. This indicates that the measured uptake is by the postganglionic ncurons and nonneural elements (NNE: glial and connective tissue cells) in the ganglia. This uptakc is not dependent on metabolic energy and is not affectcd by lowcring Na+ or raising K+ concentrations in the incubating mcdia but is depressed in the presence of ouabain and hemicholinium‐3. The presence or Na+‐dependent. rapidly saturable uptake in the preganglionic nerve terminals which is not detectablc kinetically is, however, inferred from a decrease in ACh synthesis in dcncrvatcd prcparations and a similar decrcasc in intact ganglia incubated in low Na+ solution.
REGIONAL DISTRIBUTION OF GLUTAMATE DECARBOXYLASE AND GABA WITHIN THE AMYGDALOID COMPLEX AND STRIA TERMINALIS SYSTEM OF THE RAT
Authors: Ben‐Ari Y. , Kanazawa I. , Zigmond R. E.
Published: October 2006

The distribution of glutamate decarboxylase (GAD) and δ‐amino butyric acid have been studied in the amygdaloid complex and in the stria terminalis system of the rat. The central and medial nuclei of the amygdala had significantly higher activities of GAD than the lateral olfactory tract nucleus, anterior amygdala, anterior lateral nucleus, posterior lateral nucleus, cortical nucleus, basomedial nucleus, basolateral nucleus, and pyriform cortex. The enzyme activity was about two and a half times higher in the central and medial nuclei than in the pyriform cortex. GABA was also significantly more concentratcd in these nuclei than in the pyriform cortex although this was not true for four other amino acids studied–glutamic acid, aspartic acid, taurine and glycine. GAD activity was also measured in the stria terminalis (the major afferent and efferent pathway of the amygdala) and in its bed nucleus. The enzyme activity was higher in the stria terminalis than in four other fibre tracts studied–the optic tract, anterior commissure, corpus callosum, and fimbria. GAD activity was exceptionally high in the bed nucleus of the stria terminalis particularly in its ventral part. The significance of the results are discussed in terms of what is known about the evolution and anatomy of the amygdala.
INHIBITION OF SYNAPTOSOMAL NORADRENALINE UPTAKE BY VERATRIDINE, GRAMICIDIN D AND VALINOMYCIN
Authors: White T. D.
Published: October 2006

Abstract— —The effects of brief exposures of rat brain synaptosomes to veratridine, gramicidin D and valinomycin on noradrenaline uptake were investigated. All three drugs inhibited the Na+‐dependent component of noradrenaline uptake by synaptosomes. These effects were independent of extracellular Ca2 + concentrations, indicating that the reductions were not due to the release of newly accumulated noradrenaline.

Gramicidin D reduced the Vmax for noradrenaline uptake, whereas veratridine and valinomycin reduced the Vmax and also increased the Vm for uptake.

Most of these findings can be explained on the basis of the effects that these drugs have on the inward‐directed electrochemical gradients for Na+ across synaptosomal membranes, although, in the cases of veratridine and valinomycin, the elevated Km's suggest that an impairment of noradrenaline binding to its carriers might also be involved.
ON THE SITE OF ORIGIN OF TRANSMITTER AMINO ACIDS RELEASED BY DEPOLARIZATION OF NERVE TERMINALS IN VITRO
Authors: De Belleroche J. S. , Bradford H. F.
Published: October 2006

Abstract— —The site of origin of transmitter amino acids released by depolarizing agents from nerve endings was studied. The model used was the incubated and depolarized synaptosome preparation from which the component soluble, synaptic vesicle, membrane and mitochondrial sub‐fractions were obtained. Synaptosomal amino acids were radioactively labelled from D‐[U‐14C]glucose in vivo by intraventricular injection and in vitro during subsequent incubation. The specific radioactivities of amino acids released in response to K+ (56 mM) or veratrine (75 μM) were found to closely resemble those of the soluble cytoplasmic fraction, in most cases differing significantly from those of the other fractions. The specific radioactivity of the GABA and aspartate released by K+ stimulation and the GABA and glutamate released by veratrine were significantly different from that of the vesicles in each case. The specific radioactivities of glutamate released by both agents, and also GABA with K+ stimulation, were approximately double that of the amino acid released in control conditions. Depletion of the soluble cytoplasmic pools of glutamate, GABA and aspartate occurred following stimulation, corresponding to the induced‐release of these compounds. Turnover of the amino acids in the other subfractions was too low to account for their participation in the release process in addition to the soluble cytoplasmic pool. A cytoplasmic origin of release of neurotransmitter amino acids from nerve endings is proposed.
REGIONAL TRANSPORT OF TRYPTOPHAN IN RAT BRAIN
Authors: Denizeau Francine , Sourkes T. L.
Published: October 2006

Abstract— Tryptophan uptake was studied in brain slices and synaptosomes prepared from regions known to vary in the numbers of serotoninergic cell bodies and nerve endings that they contain. The rate of tryptophan uptake was highest in hypothalamus for both types of preparation. Differences among the regions were much more pronounced in isolated nerve endings (synaptosomes). Loading with tryptophan did not affect the uptake into tissue slices. Tryptophan accumulation in hypothalamus synaptosomes was reduced after intraventricular injection of 5,7–dihydroxytryptamine whereas no change was observed in synaptosomes prepared from cerebellum under the same conditions; accumulation by synaptosomes prepared from the hypothalamic and hippocampal regions was reduced after raphe lesions.
IN VIVO LABELLING OF ACETYL‐ASPARTYL PEPTIDES IN MOUSE BRAIN FROM INTRACRANIALLY AND INTRAPERITONEALLY ADMINISTERED ACETYL‐l‐[U‐14C] ASPARTATE
Authors: Sinichkin A. , Sterri S. , Edminson P. D. , Reichelt K. L. , Kvamme E.
Published: October 2006

Abstract— Following intracranial and intraperitoneal injection of acetyl‐l‐[U‐14C]aspartate into mice about 5% and 0.7% of the radioactivity, respectively, was recovered from the brain after 30 min.

On chromatographic separation of the cationic and anionic compounds on a Dowex 50 column, the former fraction contained about 60% of the radioactivity, predominantly as labelled aspartate and glutamate. The anionic compounds, containing 20% of the labelled compounds, were fractionated in several chromatographic systems and resolved into a great variety of labelled peptidic compounds of which five acetyl‐[U14‐C]aspartyl peptides, containing two to four amino acids, were purified. One of these, acetyl‐aspartyl glutamine, has not previously been found in brain.
NEUROCHEMISTRY OF THE MUCOPOLYSACCHARIDOSES: BRAIN GLYCOSAMINOGLYCANS, LIPIDS AND LYSOSOMAL ENZYMES IN MUCOPOLYSACCHARIDOSIS TYPE III B (α‐N‐ACETYLGLUCOSAMINIDASE DEFICIENCY)
Authors: Constantopoulos George , Eiben Robert M. , Schafer Irwin A.
Published: October 2006

Glycosaminoglycans, lipids and lysosomal enzymes were measured in brain, liver and spleen of a patient with mucopolysaccharidosis Type III B (α‐N‐Acetylglucosaminidase deficiency).

The glycosaminoglycan content of the brain gray and white matter, leptomeninges, spleen and liver of the patient was 4, 3, 10, and 100 times greater than that of the respective tissues of normal controls. Partially degraded heparan sulfate, the concentration of which increased 17 times in the brain, accounted for the increased glycosaminoglycan content of all tissues.

The concentration of the gangliosides GM2, GM3 and GD3 was markedly increased in the gray matter, and to a smaller degree in the white matter. Ceramide dihexoside was also increased in the gray matter of the patient with MPS III B.

The activity of α‐N‐Acetylglucosaminidase was absent from the brain and the liver and greatly diminished in the spleen. β‐Glucuronidase. β‐glucosaminidase and α‐l‐iduronidase were more active than normally and the activity of α‐galactosidase and β‐galactosidase was markedly reduced.
VITAMIN A RECEPTORS: MULTIPLE SPECIES IN RETINA AND BRAIN AND POSSIBLE COMPARTMENTALIZATION IN RETINAL PHOTORECEPTORS
Authors: Wiggert Barbara , Mizukawa Atsushi , Kuwabara Toichiro , Chader Gerald J.
Published: October 2006

Abstract— As assessed by sucrose density gradient ultracentrifugation, bovine retinal cytosol exhibits 2S and 7S vitamin A binding species (‘receptors’). Upon fractionation of the retina, outer segment photoreceptor units are enriched in 7S receptor whereas the outer segment poor layers of the retina have a decreased amount of 7S receptor. The 2S vitamin A receptor is found both in the photoreceptor fraction and in the rod‐poor layers of the retina. The supernatant fraction of fetal retina demonstrates 2S binding but no 7S binding; a small 7S peak observed in adult pigment epithelial supernatant preparations is also not seen in the supernatant fraction of fetal pigment epithelial cells. The binding pattern in the newborn retina is similar to that in adult retina, i.e. extensive 7S as well as 2S binding. Adult bovine brain exhibits a large 7S receptor peak which is missing in fetal brain supernatant and virtually absent in newborn brain. The 7S receptor may thus be compartmentalized in retinal photoreceptors but is not unique to the retina since it is also observed in brain. The ontogenic patterns in the two tissues are different however.
BIOCHEMICAL EFFECTS IN MAN and RAT OF THREE DRUGS WHICH CAN INCREASE BRAIN GABA CONTENT
Authors: Perry Thomas L. , Hansen Shirley
Published: October 2006

Abstract— Brain amino acids were measured in rats given aminooxyacetic acid (AOAA) by mouth, and in rats given sodium dipropylacetate (DPA) both orally and by intraperitoneal injection. Brain GABA content was significantly elevated by AOAA doses of 10mg/kg/day, but not by 5mg/kg/day. Approximately 4 times as much AOAA is required by mouth as by parenteral injection to raise brain GABA content in the rat. DPA (400mg/kg) increased brain GABA and lowered brain aspartate content significantly 1 h after a single injection. However, DPA given orally (350 mg/kg/day) produced no alterations of any amino acids in rat brain.

Amino acids were measured in plasma and urine from patients treated orally with isonicotinic acid hydrazide (INH) or DPA, and from a volunteer who took AOAA. INH (10–21 mg/kg/day) increased concentrations of β‐alanine and ornithine in plasma, as well as urinary excretion of β‐alanine. DPA had no such effect. AOAA in oral doses ranging from 1.25 to 5.0 mg/kg/day increased plasma concentrations of β‐alanine, ornithine, β‐aminoisobutyric acid, proline and hydroxyproline, and produced massive urinary excretion of β‐alanine, β‐aminoisobutyric acid, and taurine.

Both INH and AOAA, given in doses practical for human use, inhibit the transamination of β‐alanine and ornithine in liver, and may also inhibit the transamination of GABA in brain. In addition, AOAA interferes with the catabolism of β‐aminoisobutyric acid, proline, and hydroxyproline. AOAA, in the lowest dose employed, appeared more effective than INH as an inhibitor of GABA aminotransferase in man, and might therefore be useful in the treatment of neurological diseases in which brain GABA is deficient.
DISTRIBUTION AND TISSUE SPECIFICITY OF GLUTAMATE DECARBOXYLASE (EC4.1.1.15)1
Authors: Wu Jang‐Yen , Chude Obi , Wein John , Roberts Eugene , Saito Kihachi , Wong Esther
Published: October 2006

Abstract— The activity of L–glutamate decarboxylase (EC 4.1.1.15) (GAD) in various mouse tissues was determined by five different methods, namely, the radiometric CO2 method, column separation, electro–phoretic separation, the filtration method, and amino acid analysis. Results from the latter four methods agreed well, showing that brain had the highest activity, 4.27 nmol/min/mg protein (100%), followed by heart (7.4%), kidney (6.3%) and liver (1.5%). Measurement of brain GAD using the radiometric CO2 assay method agreed with the other techniques. However, in heart, kidney, and liver, the GAD activities measured by the CO2 method were about 3–4 times higher than those obtained by the GABA method, suggesting that the CO2 method does not give a valid measurement of GAD activity in a crude non–neural tissue preparation. GAD activity also was detected in adrenal gland but not in pituitary, stomach, testis, muscle, uterus, lung, salivary gland, or spleen. GAD from brain, spinal cord, heart, kidney and liver were further compared by double immunodiffusion, enzyme inhibition by antibody, and microcomplement fixation using antibody against GAD purified from mouse brain. GAD from brain and spinal cord appear to be identical as judged from the following results: the immunoprecipitin bands fused together without a spur; the enzyme activity was inhibited by anti–GAD to the same extent; and the microcomplement fixation curves were similar in both the shape of the curve and the extent of fixation. No crossreactivity was observed between GAD from heart, kidney or liver and antibody against brain GAD in all the immunochemical tests described above, suggesting that GAD in non–neural tissues is different from that in brain and spinal cord.
CHARACTERIZATION OF A RAT BRAIN FUCOSYL‐TRANSFERASE
Authors: Broquet P. , Perez‐Gonzalez M. N. , Louisot P.
Published: October 2006

Abstract—

Rat brain fucosyl‐transferase was solubilized using Triton X–100 detergent, and then purified by electrofocusing.

From studies of some exogenous glycoproteinic acceptors, desialylated fetuin appeared to be the most effective substrate. Study of initial velocity patterns gave evidence for a BiBi sequential mechanism, assumed to be a random BiBi with dead end inhibition.
A CALCIUM ACTIVATED PROTEASE IN SQUID AXOPLASM
Authors: PANT Harish C. , Terakawa Susumu , Gainer Harold
Published: October 2006

Evidence for a protease in squid axoplasm which is selectively activated by Ca2+ and blocked by SH‐inhibitors is presented. This protease appears to be particularly effective in degrading squid neurofilament proteins, but also extensively degrades various other major protein components in axoplasm.
ACID AND ALKALINE PHOSPHATASES IN A BRAIN TUBULIN PREPARATION
Authors: Larsson H. , Wallin Margareta , Edström A.
Published: October 2006

The hydrolysis of p‐Nitrophenylphosphate has been studied in vitro in a tubulin preparation from bovine brain. The activity at pH 6.8 was 16.4 ± 2.2 nmol/mg protein, h.

At least two phosphatases were responsible for this activity. They were found to have pH‐optima at 5.1 and 10.4. respectively, and their apparent KM values were 1.23 ± 0.10 mm and 0.17 ± 0.03 mm. respectively. Mg2+ was found to stimulate activity at both pHs while Zn2+ inhibited at pH 5.1 and stimulated activity at pH 10.4.

All of the alkaline and part of the acid phosphatase activity were found to be closely associated with microtubules/tubulin. Tubulin purified by phosphocellulose chromatography contained phosphatase activity, and it is suggested that such activity is an intrinsic property of tubulin itself.

Phosphatase activity was also found in association with the microtubule‐associated proteins that co‐purify with tubulin. Two proteins of high molecular weight constituted the major part of the associated material. The results indicate an association of phosphatase activity with the larger of these two proteins.
CALCIUM‐DEPENDENT ALTERATIONS OF NEUROFILAMENT PROTEINS OF RAT PERIPHERAL NERVE
Authors: Schlaepfer William W. , Micro Steven
Published: October 2006

Segments of rat peripheral nerve were excised and incubated in vitro under conditions which hasten or retard the penetration of calcium into tissues. The nerve segments were then homogenized in 1%SDS, 8 M‐urea and 50mM‐dithioerythritol and the extracted proteins were analyzed by SDS polyacrylamide disc gel electrophoresis. Representative samples were also fixed and processed for electron microscopic examinations.

Incubational conditions which favored the penetration of calcium into the tissues caused widespread granular disruption of neurofilaments as well as the selective loss of 200,000, 150,000 and 69,000 MW proteins from the nerve segments. These structural and chemical changes occurred in the 24‐48 h interval during incubation at 37oC under nutrient conditions, but were accelerated under energy‐deprived conditions and with high‐calcium media. The same changes occurred in nerve segments incubated for 2h in media containing calcium with Triton X‐100 detergent or A23187 ionophore and in nerve segments freeze‐thawed in 0.5 mM‐calcium. These changes did not occur after parallel incubations in calcium‐free media. These findings support the view that 200,000, 150,000 and 69,000 MW proteins are components of neurofilaments and that they are susceptible to a calcium‐induced disruption.